Trying to impress? Derek Hough goes shirtless to reveal his muscular physique as rumoured former fling Kate Hudson shows up to watch him perform on DWTS

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He is rumoured to have been the man she turned to after splitting from fiance Matt Bellamy last year and on Monday it was Kate Hudson's turn to support Derek Hough. 

The 36-year-old actress attended the live show in Los Angeles where she saw her reported former fling take to the stage with his celebrity partner Nastia Liukin. 

While Derek donned a tux for his performance, he was spotted shirtless backstage before the show, where he showed off his muscular physique. 

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Support? Kate Hudson stopped by Dancing With The Stars on Monday night where her rumoured ex Derek Hough was performing 

Hough, 29, is clearly in excellent shape thanks to his rigorous rehearsals and was more than happy to show off the results as he strolled around the studio lot. 

Last year Usmagazine.com claimed the actress was spotted kissing Hough at a bar after splitting from Bellamy.  

A source revealed to the publication that Kate and the dancing pro 'were totally kissing' as they hung out at West Hollywood hot spot The Nice Guy - days before the split announcement was made by Kate's rep. 

Linked: He is rumoured to have been the man she turned to after splitting from fiance Matt Bellamy last year and on Monday it was Kate's turn to support Derek

On show: Hough, 29, is clearly in excellent shape thanks to his rigorous rehearsals and was more than happy to show off the results as he strolled around the studio lot

However, they are not believed to still be together. 

Meanwhile, the final four couple’s did not disappoint during the Dancing With The Stars semi-final on Monday.

With the competition tighter than ever, it was clear that all couples were out to impress as they performed their two dances of the night.

Rumer Willis once again put on a dazzling display with her partner Val Chemerkovskiy as they kicked off the show with a passionate Viennese Waltz. 

Sensual: Rumer Willis and Val Chemerkovskiy put on quite the show as they performed a captivating routine on the Dancing With The Stars semi-final

‘You were a perfect Anastasia. Your mother is completely right, America is falling in love with you, Rumer,’ said Julianne.

Bruno called the dance ‘steamy’ without losing the ‘lyrical quality’ that kept it ‘sensual but romantic.’

Carrie said Rumer was ‘connected’ to the story and the movement and she had been ‘a vision in white’ out on the floor. 

After the dance Rumer got a big hug from her mother Demi Moore, who was on hand to cheer for her alongside friends and family.

Rumer and Val received a 10, 9, 9 and 10 for a total score of 38.

 Stunning: Rumer kicked off the show with Val Chmerkovskiy performing a passionate Viennese Waltz

Racy: The impressive dance was inspired by the 50 Shades of Grey trilogy

Near perfect: Rumer and Val received a 10, 9, 9 and 10 for a total score of 38

Next Noah Galloway danced the Viennese Waltz with dance partner Sharne Burgess.

Julianne said she liked the fresh approach to the dance and called it a smooth routine, while Bruno described it as ‘beautiful and unexpected.’

Len called the routine Noah’s best dance and called it ‘emotional.’

Things certainly did get emotional when Noah took the opportunity to propose to his girlfriend Jamie live on air.

Embrace: Demi and her daughter Rumer hugged it out once she had finished her dance 

She couldn't be Moore proud: Demi even spoke about her divorce from husband Bruce Willis on the show and said how it had the biggest impact on Rumer 

Flawless: Demi looked stunning as ever as she spoke about Rumer's childhood

Carrie Ann called it an ‘incredible’ dance and was thrilled to watch Noah have fun out on the dance floor.

Next Riker Lynch and Allison Holker performed a contemporary dance. 

‘Yet again right on target, that had such a gutsy physicality. It is extremely difficult even for a professional to attempt a dance like that. It was incredible,’ said Bruno.

Dirty Dancing: Rumer has built up quite a reputation when it comes to her raunchy routines 

Carrie Ann praised him for being ‘vulnerable and raw’ in his performance. ‘You were killing it,’ she said.

‘That was a great performance,’ said Len, while Julianne admitted she could not actually tell who the professional dancer was.

The judges gave them four 10s for a perfect score of 40.

‘That was unbelievable, I am loving every moment of this,’ said Riker.

Proud mama: Demi was seen looking speechless during the show 

Sister support: Tallulah Willis was also seen cheering on her sister 

Impressed: Rumer and Val certainly appeared to be pleased with their results 

The final dance of the first round saw gymnast Nastia Lukin perform a quickstep with Sasha Farber. 

Carrie Ann described the performance as a ‘showstopper’, while Len said Nastia had displayed speed and control.

Bruno called Nastia a blonde bombshell and a star.

‘I feel like you are now a dancer and not just a gymnast. That was amazing,’ said Julianne.

All of the judges gave the couple 10s for a perfect score of 40.

Host Tom Bergeron said the big smile put an end to the ‘cranky’ Nastia image.

Is this REALLY happening? Army veteran Noah Galloway proposed to girlfriend Jamie Boyd Best live on tonight’s semi-final of Dancing With the Stars on Monday night's show

Near perfect scores: Noah was already riding high after he and dance partner Sharna Burgess 

Fresh: Julianne said she liked the fresh approach to the dance and called it a smooth routine, while Bruno described it as ‘beautiful and unexpected’

 Touching: Len called the routine Noah’s best dance and called it ‘emotional'

Big night: Noah and Sharna got all '9s' from the judges on the night 

In the intermission the cast of Dancing With the Stars Perfect 10 Tour, performed along with special guest Melissa Rycroft.

For the second half of the semi-finals the show broke new ground, giving the judges creative control of the couples for the first time ever.

Len, Julianne, Bruno and Carrie Ann swapped the judging table for the dance floor as they coached and even actually took part in the dances.

Good scores: Riker Lynch and Allison Holker performed a contemporary dance

Wow: The pair managed to sweep the board as they received perfect tens from all four judges

On top of giving dance advice the judges also chose the couples’ song, dance style and wardrobe.

First up Bruno chose Rumer and Val and helped them prepare a contemporary to Swan Lake, saying that he wanted a passionate couple to perform for him.

In the build up Val admitted some concerns with the difficult routine.

‘I don’t know why if you are from Eastern Europe everyone presumes you can do ballet,’ he grumbled to the cameras.

Derek's return! DWTS also saw a previously injured Derek Hough return to the dancefloor with Nastia Liukin

Backstage: The show also saw judge Bruno Tonioli rehears with Rumer and Val for a special dance 

At the ballet: Rumer and Val rehearse in a dance studio before the show 

Rumor admitted that it was a ‘risk’ to do it but was up for the challenge.

And with Val in white tights, the ballet-themed performance ended with a dramatic lift.

Len told the couple that he would have them highest rated on his own private leaderboard as he complimented Rumer’s ‘brilliant dancing.’

Julianne did her best Bruno impression as she called the dance ‘beautiful.’

Carrie Ann called it ‘genius, but a little mad’ and told Rumer she had pulled off a difficult routine and nailed the lift.

Black Swan: For the second part of the show, Rumer put on another impressive performance 

Poised: The talented dancer showed off her ballet skills 

‘I am very relieved and very happy. These kids are brilliantly talented,’ Bruno gushed.

The judges gave the couple three 10s for a perfect score of 30, giving them 68 out of 70 for the night.

Carrie Ann Inaba then helped Noah Galloway and Sharna Burgess with their matador-themed Paso Doble.

‘I want to see what it took for Noah to go from wounded, depressed, lost all self esteem, to where he is now,’ said Carrie Ann before the dance.

Dynamic duo: Rumer and Val appear to be staking their claim for a place in the final 

Swanning off: Rumer and Val were the undisputed showstoppers of the evening 

‘It is an honor to be part of his story,’ said Carrie Ann as she fought back tears.

Julianne said she was given chills by the dance and called it one of Noah’s best yet, while Bruno said it was ‘absolutely masterful.’

‘You came out and gave us a battle, it had all the excitement of the bullfight. Conceived by Carrie Ann, believed by Sharna and achieved by Noah,’ said Len.

All three judges gave the couple 10s, for a perfect 30, giving them a total of 66 out of 78.

Riker Lynch and dance partner Allison Holker got help from Julianne Hough on their Argentine Tango.

Men in tights! Val had to get into the spirit of things for a special ballet themed dance on the show 

Tough decisions: It's getting harder for the judges, as they try and make decisions for the semi finals 

And Julianne took her coaching duties extra seriously as she stepped from behind the judges table and back out onto the dance floor as part of the routine.

River was excited to work with Julianne, who is actually his cousin

‘Len, Bruno and Carrie Ann better watch out - just kidding, I love you guys,’ said Julianne playfully as she got ready to dance for the first time in the season.

Bruno told Riker that he had controlled the dance ‘like a lion tamer’, while Carrie Ann said he did not just handle a champion like Julianne, but danced like one.

Snapping at their heels: Riker Lynch and Allison Holker also put in a very good second performance

‘You have become a triple threat, you always had flair, now add musicality, great technique, put into the mix Julianne and wooaah,’ gushed Len.

All of the judges gave the couple three 10s, for a perfect overall score of 70.

Len Goodman, 71, then partnered with healthy-again Derek and gymnast Nastia Lukin and made his own emotional cameo in their dance.

‘In ten years I have never been judged for anything other than my judging. I am old now, I have arthritis in my knee and I can’t dance,’ explained Len.

‘For everyone there comes a time when you can’t do something, but you always look back and think about how it was and what it was like.

‘Sometimes I get that feeling of ‘gee I wish I could dance like that.’ And that is what I want this to be.’

 Arms wide: Derek was back in good form as he worked the dance floor with his star partner Nastia

Joining in: Natsia also danced with head judge Len as part of the fun twist in the second half of the night

So they put together a routine based on how Len used to dance as a younger performer.

‘I want Derek to be like I used to be - only 20 times better and 50 years younger,’ said Len.

Derek admitted it was upsetting to hear Len talk bout how his body has ‘betrayed him’ as he said he wanted to nail the routine for his mentor.

And at the end of the dance Len, wearing his tuxedo, stepped out onto the dance floor to dance with Nastia in a classic and poignant moment for the show.

Dipping her gently at the end, Len pointed at the camera and saluted.

‘Wow. Len, it was incredible. I was in tears and then Len came out and watching that delicacy was a true moment. I will remember that forever,’ said Carrie Ann.

Choking on tears of her own, Julianne, who has known Len since she was nine, called it ‘the most special dance I have ever seen.’

Bruno was also mesmerized praising the dance’s ‘nostalgic warmth and love and dedication to this art form’ as he thanked Len for everything.

Erin handed out tissues as Len told her ‘it was lovely’ to be part of the dance.

All of the judges gave them 10s giving the couple a perfect 70 out of 70 for the evening.

Fine dining: Maksim Chmerkovskiy and Peta Murgatroyd were later seen leaving Craig's restaurant

All smiles: The pair rocked laid-back styles for their night out at the eatery in Melrose