NFL expert handicapper Mike Tierney has become a master at finding the right underdogs to back. He has done it with success in the opening two weeks of the season, so you'll definitely want to hear his NFL underdog picks for Week 4. No one knows the NFL like the "Top Dog," the national sportswriter who has reported from seven Super Bowls. He has his finger on the pulse of the league and excels in against-the-spread and straight-up picks. 

Tierney knows a good upset pick when he sees one. He absolutely crushed both of his NFL upset picks in Week 1, taking the Bengals (+3), who won 34-23 at the Colts, and the Dolphins (+1.5), who won 27-20 at the Titans. In Week 2, he picked the Dolphins again straight up (+3) against the Jets. Miami led 20-0 at halftime in a 20-12 victory, another easy winner for Tierney and his followers. 

Now Tierney has studied the matchups and revealed a pair of confident upset picks for Week 4. We can tell you one of those teams is the Lions, three-point underdogs at the Cowboys. A winning $100 straight-up bet on Detroit would bring in $150. He has another ultra-confident upset pick, posted exclusively at SportsLine. 

Tierney knows the Cowboys' offense has been an unproductive mess this season. Dallas (1-2) is averaging just 13.7 points, better than only the hapless Cardinals. The Cowboys racked up 20 points in a 20-13 victory over the Giants in Week 2, but 21 total points in losses to the Panthers and Seahawks

Despite Ezekiel Elliott and his solid 274 yards and 5.7 per-carry average through three games, the offense ranks 30th in total yards. Dak Prescott has thrown for just 498 yards -- 145 per game -- with two touchdowns and two interceptions. He has been sacked 11 times. 

The Lions (1-2), meanwhile, have improved each week. After a humbling 48-17 loss to the Jets in Week 1, Detroit was edged by on the road the 49ers 30-27, but rebounded in a big way, hammering the Patriots 26-10 on Sunday night. 

Detroit signed LeGarrette Blount to help shore up one of the league's bottom running units, but instead it has been rookie Kerryon Johnson who has impressed, rushing for 161 yards (5.6 per carry). Matthew Stafford has been his usual high-production self, averaging 295 yards. The offensive line in front of him has allowed just three sacks.

"If and when the Lions win Sunday, it will be labeled an upset," Tierney told SportsLine. "But not by me." 

His other underdog pick is a team many experts, and Vegas oddsmakers, are overlooking, but Tierney points to two critical x-factors that he says turn this underdog into a favorite. 

So what is Mike Tierney's NFL underdog pick of the week? And what team is Vegas greatly overlooking? Visit SportsLine now to see which underdog team shocks the world in Week 4, all from the expert who has crushed the sportsbooks with his NFL picks, and find out.