Heat lightning lit up the desert sky Friday night in the fourth quarter of the Bears' 27-17 exhibition loss to the Arizona Cardinals at Sun Devil Stadium. Unless the Bears caught some of that lightning in a bottle, they returned to Halas Hall for practice Sunday with more concern than hope.

One two-play sequence in the first quarter illustrated how the Bears' offensive line tenuously holds the key to their season more than any running back they could import next week, more than any free-agent quarterback they signed last spring.

On second-and-1 from their own 37, Bears running back Anthony Thomas took off for a nice 9-yard run that was negated by a holding penalty by guard Chris Villarrial. On the same play, left tackle Mike Gandy left the game with an apparent leg injury that didn't turn out to be serious.

A play later, Gandy's replacement, Steve Edwards, let Cardinals defensive end Calvin Pace blow past him to pressure Bears quarterback Kordell Stewart. A harried Stewart altered his delivery and threw a pass intended for Marty Booker into the arms of cornerback Coby Rhinehart, who returned it 17 yards to the Bears' 27.

"Turnovers always kill you in any football game," coach Dick Jauron said.

Two plays later, kicker Tim Duncan nailed a 43-yard field goal to give the Cards the early momentum and a 10-3 lead with nine seconds left in the first quarter.

And what a rough first quarter it was for the Bears' offense—especially up front.

Of the Bears' first six plays, the Cardinals sacked Stewart three times. Then on the final play of the quarter, Stewart was rushed into dumping the ball off to tailback Adrian Peterson, who fumbled at the 14 and the Cardinals' Kenny King recovered.

Arizona needed only two plays to score on a 12-yard pass from Jeff Blake to tight end Freddie Jones over Bears rookie Lance Briggs. That made it 17-3 Cardinals, with the Bears' points coming on a 51-yard field goal by Paul Edinger with 8:11 left in the first quarter.

The Bears' No. 1 offense salvaged some respect with a 10-play, 90-yard march with 2:53 left that culminated with a 20-yard TD pass to tight end Desmond Clark that made it 17-10. But even that drive included an embarrassing moment for the Bears. David Terrell punted the ball in celebration of an apparent 13-yard TD catch only to be flagged for offensive pass interference that nullified the score.

The second offense provided the night's best Bears highlight when quarterback Chris Chandler lofted a perfect 37-yard pass into the arms of receiver Edell Shepherd to tie the score at 17-17 with 1:01 left in the third quarter.

Rookie Rex Grossman took over for Chandler early in the fourth quarter and took a step backward with two interceptions. Cornerback Robert Cromartie picked off a Grossman pass thrown right to him at the 11:18 mark, and the Cardinals converted that mistake into the go-ahead touchdown. Grossman threw his second interception to Justin Lucas in the end zone with 3:52 left and the Bears threatening to tie from the 4-yard line. Five plays later, Bill Gramatica hit a 50-yard field goal for the final margin.

Grossman's turnovers bothered Jauron almost as much as defensive end Alex Brown's. Brown intercepted a Jeff Blake pass in the second quarter after batting it into the air in an impressive display of athleticism. What followed wasn't so impressive. Brown fumbled after an 11-yard return, and it was recovered by the Cardinals' Anquan Boldin.

"We can't turn the ball over when we get it," Jauron said. "That was a huge play by Alex, but he's got to protect the football."

The way Stewart moved the football when the Bears got the ball back encouraged Jauron. Stewart completed 7-of-8 passes, skillfully running the two-minute drill, one of the few positives on which the Bears will build.

"It was good to see Kordell executing the two-minute offense," Jauron said. "He can play better, but he also made some big plays. He has a lot of confidence, the players have a lot of confidence in him, and that's a big plus."

Overall, Stewart completed 13-of-18 passes for 139 yards, impressive considering that he seldom had adequate time to find his receivers. Bears running backs showed more than they did against the Broncos, but probably not enough to stifle Bears fans from clamoring for the team to trade for Eagles running back Duce Staley.

A league source said Staley decided to end his 26-day holdout over his $2.2 million salary and report to the Eagles on Sunday. The Bears have not yet discussed a trade for Staley and don't expect the Eagles to put him on the market because they maintain Super Bowl aspirations and still wonder about their untested backups Correll Buckwalter and Brian Westbrook.

If the Eagles do shop Staley, the Bears obviously would listen, but Bears general manager Jerry Angelo said publicly last week that he "likes our backs," and Bears players openly have supported Thomas.

Thomas—who had 12 yards on three carries at halftime—ran effectively at times in the first quarter, his best run a nifty 9-yard cutback. But there aren't many running backs who would have found room running behind the Bears' offensive line Friday night.

The Bears' defensive line fared only slightly better and appeared to be adjusting to its subtle change in style. In the past, the Bears' defensive tackles often served as little more than glorified roadblocks keeping offensive linemen from getting to linebackers. But having watched the way Tampa Bay successfully unleashed its defensive line on its way to a Super Bowl, coordinator Greg Blache decided to ask his interior linemen to not just get in the way of blockers, but get upfield too.

The defensive line didn't get in the way as much as it had hoped in the first half Friday on a night when stopping the run was a priority. The No. 1 defense gave up 46 rushing yards on 12 carries.

The run defense started poorly on second-and-goal from the Bears' 4 with 11:18 left in the first quarter when Emmitt Smith made Brian Urlacher miss and scooted into the end zone to make it 7-0 Cardinals. A frustrating night had begun.