Breakdowns on special teams, including a high snap from center that resulted in a fourth-quarter safety, and two missed field goals led to the loss in Soldier Field.
Greg Davis booted a 31-yard field goal as time expired, his third of the game, and the Phoenix Cardinals (2-0) edged the Bears 11-10 in front of 51,748.
"For the most part, the effort was outstanding, and I was very pleased with the defense," said Bears coach Dave Wannstedt. "There were a lot of opportunities that we didn't take advantage of. I told the guys that every player in that room had chances during the game to make plays. In order to give ourselves the best chance to win, we need playmakers."
Anthony Morgan was knocked unconscious on the Bears' first possession. A third-down pass from Jim Harbaugh sailed high and wide and Cardinals safety Chuck Cecil leveled Morgan. He was carried off the field on a stretcher and taken to Northwestern Hospital for further examination.
A little later, first-round pick Curtis Conway, also the Bears' main kick returner, suffered an ankle injury. It was X-rayed, diagnosed as a sprain, and he sat out the rest of the game.
"I hurt it on the second kickoff, and I don't know how exactly," said Conway. "I didn't feel anything until I got up and tried to put pressure on it. I went out for the next play and I could barely stand up."
Without Morgan and Conway, said Wannstedt, "we didn't have the personnel we needed to throw the ball. So Jim (Harbaugh) was a little disadvantaged right off the bat, not being able to go deep."
The Cardinals took over at midfield following an early 28-yard punt by Chris Gardocki. Former Bears running back Johnny Bailey picked up 17 yards on three carries. Steve Beuerlein passed 12 yards to Randal Hill and 13 yards to Ricky Proehl.
But the Phoenix drive stalled at the Bears' 4 when linebacker Joe Cain stopped running back Ron Moore for a yard loss and Richard Dent sacked Beuerlein for a five-yard loss on third down. So Davis booted a 28-yard field goal to put the Cardinals on top 3-0.
Trace Armstrong's 8-yard sack of Beuerlein put the Cardinals on their 10 late in the first period. A third-down pass intended for Hill was picked off by free safety Mark Carrier, who returned it 16 yards to the Phoenix 14.
"We were just fortunate to get good pressure on the quarterback," said Carrier, whose steal set up Kevin Butler's 27-yard field goal for a 3-3 tie.
Another Phoenix turnover gave the Bears the ball at the Cardinals' 43. Moore fumbled when hit by defensive tackle Chris Zorich, and Armstrong recovered with :52 left in the first quarter. But a 46-yard kick by Butler sailed wide left.
Harbaugh was 6 of 11 for only 28 yards in his first-half stint. He ran four times for 22 yards. The running game continued to struggle. The Bears rushed for 57 yards on 26 carries, a 2.2-yard average.
"I was a little disappointed in our running game early. We had too many negative plays," said Wannstedt. "We got caught second and 10, secondand 11, and then you are fighting an uphill battle."
The Bears netted only three first downs and 47 yards in the first half. They wound up with 12 first downs and 114 total yards.
"We have to do a better on our first-down plays," said Harbaugh. "We need to get the running game going."
The Cardinals had nine first downs and 122 yards at halftime, but the score remained 3-3, thanks to three Phoenix turnovers, including a Donnell Woolford interception return of 31 yards just before the half ended.
Dent had two first-half sacks, and Maurice Douglass got one on a safety blitz.
Peter Tom Willis (5 of 9 for 56 yards) took over for Harbaugh in the third quarter and directed an eight-play, 78-yard drive. A 15-yard pass to fullback Craig Heyward and a 34-yard interference penalty on the Cardinals' Nathan LaDuke, trying to cover Terry Obee, set the Bears up for their first preseason touchdown.
Darren Lewis (24 yards on 14 carries) did the honors from a yard out for a 10-3 lead.
Willis led the Bears on another long drive. But it stalled at the 17, and Butler's 35-yard kick hooked wide left.
The Cardinals closed to 10-6 on a 45-yard field goal by Davis with 6:21 left.
Then Gardocki lined up for a punt, and center Jay Leeuwenburg snapped the ball over his head into the end zone. Gardocki fell on it for a safety, and it was 10-8 with 4:17 to go.
"That was a shame . . . Jay has been doing a good job," said Wannstedt. " "But we can't let it happen. There were a lot of lessons to be learned."