Undefeated teams clash when the Buffalo Bills (4-0) visit the Tennessee Titans (3-0) on Tuesday night. Buffalo is a 3.5-point favorite and the over-under is 52 in the latest Bills vs. Titans odds from William Hill. Before locking in any Titans vs. Bills picks, you NEED to see what SportsLine's all-time No. 1 NFL expert, Mike Tierney, has to say. 

A renowned sportswriter whose work appears periodically in the New York Times and Los Angeles Times, Tierney has covered the NFL for decades and reported from seven Super Bowls. All-time at SportsLine, Tierney has returned $3,754 to $100 bettors.

Tierney also has an uncanny feel for these teams: He is 7-1 in his last eight against the spread picks for or against Buffalo, including nailing the Bills' covers in Weeks 3 and 4, and 15-8 on picks involving Tennessee, a combined 22-9 run on these teams. 

Now, Tierney has dialed in on Bills vs. Titans from every possible angle. We can tell you he's leaning Under the total, and he's also found a critical X-factor that has him jumping all over one side of the spread! You ABSOLUTELY need to see it before you lock in your own picks.

So who wins Bills vs. Titans on Tuesday night? And what critical X-factor makes one side of the spread a must-back? ... Join SportsLine right now to see which side of the Bills vs. Titans spread you should be all over on Tuesday, all from the expert who's 22-9 on picks involving these teams!