As it turned out, the Chicago Bears had plenty of concerns about the speedy, dual-threat running back they couldn't slow down.
Bush's 37-yard touchdown run helped Detroit score 27 points in the second quarter and he accounted for 173 yards of offense to help the Lions beat Chicago 40-32 Sunday.
"I was a little nervous," Bush said of his knee after missing a game with the injury.
Detroit (3-1) moved into a first-place tie with Chicago (3-1) in the NFC North.
Bush had a season-high 139 yards rushing and a score on 18 carries, mostly up the middle as he took advantage of running lanes created against a line without defensive tackle Henry Melton.
"We felt like we could dominate the line of scrimmage in this game, especially after they lost a key player to injury," he said.
The Lions scored 24 straight points, including three TDs in a span of 3 minutes, 26 seconds, after Matt Forte's 53-yard TD run gave the Bears 10-6 lead early in the second quarter.
Detroit led 40-16 early in the fourth quarter and ended up needing that cushion.
Jay Cutler, who had four turnovers, threw a pair of touchdown passes and 2-point conversions in the final 4 minutes to pull Chicago within eight points. Lions receiver Kris Durham recovered the onside kick to seal the win.
"There are no moral victories, but I thought our guys played tough for the last 30 minutes of that game," Chicago coach Mark Trestman said.
Detroit had a big lead to work with thanks to positive plays it got from each facet of the game.
Micheal Spurlock's 57-yard punt return set up Matthew Stafford's go-ahead TD with 6:09 left in the first half, when he recovered his own fumble on a 1-yard sneak. Stafford threw a 2-yard TD to Calvin Johnson on the Lions' next possession, one play after safety Glover Quin returned Cutler's second interception for 42 yards.
"This wasn't a one-man victory," Stafford said.
Bush, though, just as he did in his Detroit debut in a Week 1 win over Minnesota, was the star of the day.
He burst through a huge hole and hurdled safety Major Wright to give the Lions a 30-10 lead, their highest scoring first half in franchise history against Chicago, showing they didn't miss Nate Burleson very much. Burleson, the team's No. 2 receiver, broke his left arm in a one-car accident last Tuesday.
Stafford completed 23 of 35 passes for 242 yards with a TD, an interception and a lost fumble.
Cutler hurt the Bears opportunity to come back late in the third quarter when an up-for-grabs pass was picked off by safety Louis Delmas, who had two interceptions for the first time in his five-year career.
Stafford, though, turned the ball over again to give Chicago a chance - briefly. His low pass intended for Johnson inside the Bears 10 was kicked up in the air and intercepted by Wright.
Three snaps later, Ndamukong Suh sacked Cutler for a second time and forced a fumble that fellow defensive tackle Nick Fairley recovered and returned 4 yards for a score that put Detroit up 37-16 late in the third.
He tripled that total in one afternoon, fumbled for a fourth turnover and was sacked three times after being taken down that many times combined in three games this season.
"Any quarterback, you hit him enough times, I'm sure they'll get rattled," Fairley said. "I think we hit him enough times to rattle him, but he didn't show it."
Cutler, who was 27 of 47 for 317 yards, rallied with a 14-yard TD pass to Alshon Jeffery with 4 minutes left and a 2-yard conversion pass to the same receiver that pulled Chicago within 16 points.
"I felt good about my decision making," he said. "I just missed some throws."
Cutler connected on some more later, but it was too late. He threw a 10-yard TD pass to Earl Bennett with 43 seconds left and found Brandon Marshall for a 2-point conversion that made it 40-32, making a game that was lopsided for much of the game appear to be close.
"Three picks and a fumble, it's hard to come back from," Cutler acknowledged.
NOTES:Lions CB Rashean Mathis left the game in the first half with a concussion and didn't return, and CB Chris Houston didn't finish the game because of a leg injury, Schwartz said. ... Forte finished with 95 yards rushing on 14 carries.
Copyright 2013 by The Associated Press