An NFC East showdown with major implications for the divisional title highlights the Sunday afternoon NFL slate as the Dallas Cowboys visit the Washington Redskins at 4:25 p.m. ET. Both teams are looking to build on perhaps their most complete performances of the season. Washington seeks its third consecutive home victory after it downed the Carolina Panthers, 23-17, last week, while the Cowboys are seeking their first two-game winning streak of the season and head to FedEx Field with momentum following a 40-7 drubbing of the Jaguars. The spread has moved back and forth all week, with the Cowboys favored by 1.5 in the latest Cowboys vs. Redskins odds. The over-under for total points scored is 41. Before you lock in your Cowboys vs. Redskins picks, make sure to check out what SportsLine expert Mike Tierney has to say.

Tierney is a widely respected national sportswriter who also has emerged as one of the top handicappers for SportsLine. He's currently the top NFL analyst this season with an impressive spread record of 23-7, but his credentials are even more astounding when it comes to these two clubs. Over the past two seasons, Tierney is 28-7 on against-the-spread picks involving Dallas or Washington, which includes an unheard-of mark of 11-0 on the Redskins.

Two weeks ago, Tierney told SportsLine members to anticipate a flat spot for the Redskins when they visited the Saints. The result: New Orleans rolled to a 43-19 win behind a record-setting night from Drew Brees, and anyone who followed Tierney's advice pocketed an easy winner. 

Now, he has scrutinized Cowboys vs. Redskins from every possible angle to reveal a strong point-spread pick that he's sharing only at SportsLine. 

Tierney knows Washington will attempt to build on one of its best defense defensive performances of the season. The Redskins forced three turnovers against Carolina while also holding the Panthers to 3 of 9 on third-down attempts. Josh Norman had an interception and a forced fumble as Washington bounced back from a dreadful defensive performance in its loss to New Orleans. 

The Redskins now rank No. 5 in total defense, allowing 326.2 yards per game. Their scoring defense (20.8 ppg) ranks No. 8 in the NFL. 

Just because the Redskins have been playing stout defense doesn't mean they'll cover on Sunday.

The Cowboys were a trendy pick to perhaps contend in the NFC East, but they were hampered by an offense that lost tight end Jason Witten to retirement and lacks a game-breaking receiver. Losses in two of their first three games while scoring 41 combined points had fans of "America's Team" restless and coach Jason Garrett's job security came into question. But the heat has subsided now that the Cowboys have won two of three and can take the division lead with a victory on Sunday. 

The Cowboys hope to continue a trend that has seen the road team dominate this series. The Cowboys have covered on their last four trips to Washington and the road team is on a 7-1 ATS run in this rivalry. They also hope to reverse a trend that has seen them lose a road game on every odd week so far this season.

We can tell you Tierney leans toward the Over, but he has identified the crucial X-factor that makes one side of the spread a must-back. He's only sharing it at SportsLine. 

Who covers the Cowboys vs. Redskins spread? And what crucial X-factor determines the point-spread winner? Visit SportsLine now to see which side of Redskins-Saints you need to jump on Monday, all from a renowned sportswriter who's an insane 11-0 picking Redskins games.