Mitchell Trubisky passed for 338 yards and three touchdowns, including the go-ahead, 3-yard score to David Montgomery with 2:17 left, and the Chicago Bears spoiled a surprisingly strong NFL debut from David Blough with a 24-20 Thanksgiving Day win over the host Detroit Lions.Montgomery rushed for 75 yards on 16 carries and caught two passes for 12 yards. Anthony Miller caught nine passes for 140 yards, while Allen Robinson hauled in eight for 86 yards and a touchdown for the Bears (6-6), who have won two in a row.Blough, a third-string quarterback, passed for 280 yards and two touchdowns before getting picked off on the team’s final possession. Kenny Golladay had four receptions for 158 yards and a 75-yard touchdown for the Lions (3-8-1), who have lost five straight and eight of nine.Detroit’s longtime starting quarterback Matthew Stafford missed his fourth consecutive game with a back injury. Second-stringer Jeff Driskel didn’t start due to hamstring soreness.Trubisky engineered a nine-play drive in the third quarter that tied the game at 17-all. The Bears finished it off with an 18-yard hookup from Trubisky to Jesper Horsted, who made a diving grab with 4:44 left in the quarter.Matt Prater’s 24-yard field goal gave the Lions a 20-17 lead with 10:47 remaining.Pass plays of 35 and 32 yards to Miller, both on third down, set up Chicago’s game-winning drive, which began at its own 10. Trubisky then found Montgomery over the middle for the touchdown.With 2:12 to play and starting from their own 17, the Lions drove to the Bears 26, but a third-down sack made it fourth-and-22 before Blough was picked off by Eddie Jackson.