Garcia, making his second start in place of Joey Harrington, rolled right and tried to throw back across the field to Mike Williams. Tillman stepped in front of the soft toss and raced untouched to the end zone where he was mobbed by teammates.
"The ball was floating," Tillman said. "But my eyes weren't big until I caught it and knew I would score."
"This is my third year in the league and it's my first time in first place," Tillman said. "It's feeling pretty good. I'm going to savor the moment." Meanwhile, Garcia regretted trying to make plays that weren't there.
The 35-year-old quarterback was bailed out after one ill-advised play in the fourth quarter, then the Bears burned him on another in overtime.
"This was an emotional game," said a distraught-sounding Garcia. "You battle for 60-plus minutes, and it falls on your shoulders to make a play, and you don't do it. Right now, it hurts."
Thomas Jones fumbled on the ensuing drive at Detroit's 28, then the Lions caught a huge break on the next play.
"I guess if you argue enough with the refs, they're going to change the call in your favor," said Urlacher, referring to Lions coach Steve Mariucci's lobbying efforts. "They should've had to review the play, not us. But we won the game, so it doesn't matter."
Chicago overcame the call and won its third straight, becoming the first NFL team with 650 victories.
Orton's 23-yard pass to Muhsin Muhammad, which capped a 99-yard drive, and Robbie Gould's two field goals put Chicago ahead 13-3 at halftime.
They went 85 yards on 12 plays, capped by Kevin Jones' 6-yard run to pull to 13-10 with 3:05 left in the third quarter. Chicago hadn't allowed a TD in the previous two games, or a rushing score all season.
Hanson's 30-yard kick tied it at 13 early in the fourth quarter.
The Bears were driving with a chance to go ahead when defensive tackle Shaun Cody caused Jones to fumble and defensive end Kalimba Edwards recovered. Jones injured his ribs on the play, and finished with 72 yards rushing. Smith said Jones would be OK.
Lions tackle Jeff Backus, a first-round pick in 2001, said it was the franchise's most meaningful game in four-plus seasons and its first significant game in October. Detroit defied the NFL's trademark parity with a 16-48 record from 2001-2004.
"This is a tough game and a tough loss," Mariucci said. "We fought back from a 13-3 deficit and we had some other chances, but they got us on the last play.
"We have to find a way to win these games, not come close."
Notes: Bears WR Mark Bradley sprained his right knee and was carted off the field late in the first half, with five receptions for 88 yards. ... Lions DT Shaun Rogers (knee), receiver Roy Williams (knee) and Bears OG Ruben Brown (chest) were inactive. ... The Bears won for the first time in four games at Ford Field. ... There was a moment of silence for Rosa Parks and Wellington Mara. ... Lions LB Teddy Lehman (foot), FB Paul Smith (ankle), FS Terrence Holt (concussion) and DE Cory Redding (shoulder) were hurt during the game.