With the job half done, Illinois was equipped with a 10-point lead, the ball and the memory of a nine-minute drive when its offense battered the Missouri defense to open Saturday's game.

But instead of becoming the moment the Illini took control, they sputtered, then smoked and stalled to open the third quarter.

An impressive first half under the leadership of quarterback Nathan Scheelhaase in his first college game gave way to a scoreless and lethargic second half as Mizzou pulled away 23-13 at the Edward Jones Dome.

"We just came out flat in the second half,'' running back Mikel LeShoure said. "I'm not sure what it was. Maybe people were a little comfortable and thought the game was over. But we did come out flat.''

Illinois ran the ball impressively in the first half on the way to a 13-3 lead but couldn't find enough openings to sustain any drive after halftime.

And with Scheelhaase struggling to throw the ball, the Illini seemed to lose control of the game, even as they clung to a lead.

"In the first half we played well. I think we began to lose it at the start of the third quarter,'' coach Ron Zook said. "We talk about that all the time. We came out and kind of stumbled around a little bit in the third quarter.''

Playing what Zook called the team's best game in the last four outings against Mizzou gave the Illini a dose of encouragement as they head home for games against Southern Illinois University Carbondale and Northern Illinois.

But the inability to sustain anything offensively after a solid start was ultimately frustrating.

Illinois had 196 yards in the first half, when Scheelhaase threw a 13-yard touchdown pass to A.J. Jenkins and Derek Dimke kicked two field goals. But the Illini managed only 85 yards in the second half.

The Illini plummeted from 157 rushing yards in the first two quarters to 43 in the second half. After rushing for 82 before halftime, Scheelhaase was dropped for negative six yards.

"I didn't feel any difference at all,'' Scheelhaase said. "Running plays were there to be made. I missed on a couple of them. We probably built more confidence in the first half, and in the second we didn't make plays when we needed.''

The defense, meanwhile, held up fairly well under difficult circumstances. Mizzou unleashed an aerial assault against a secondary riddled with injuries, but Blaine Gabbert didn't get the Tigers into the end zone until the second half.

The Illini were helped by an offensive pass interference call against the Tigers and several dropped passes. But ultimately they held together better than many anticipated.

"We lost, so obviously we didn't play well enough,'' first-year defensive coordinator Vic Koenning said. "I don't think we gave up 600-something yards like someone prognosticated, but a loss is a loss.''

Illinois surrendered 379 yards, with all but 98 coming via Gabbert's arm.

The Illini might have been in better shape at halftime if not for some ill-timed penalties.

After reaching the 3-yard line in the first quarter, tackle Jeff Allen was called for a false start. The Illini eventually settled for Dimke's 21-yard field goal and a 3-0 lead.

On their next possession, a holding call against guard Randall Hunt wiped out a first down inside Missouri territory. Illinois then lost the ball on a fumble as Scheelhaase was scrambling to make up the lost ground.

"We hurt ourselves when we got down there in the first half with stupid penalties,'' first-year offensive coordinator Paul Petrino said. "We got to the (32) in the fourth quarter and had a turnover. We've got to eliminate the turnovers and stupid penalties, then we'll give ourselves a chance to win.''

Scheelhaase had little success through the air, completing nine of 23 passes for 81 yards with three interceptions. Meanwhile, the Illini forced only one turnover and seemed to be on their heels defensively in the second half.

It was a difficult way for Illinois to end the Arch Rivalry series and yet another reminder of why another home game in future years could be helpful. But it was a performance that gave Zook hope for 2010.

"You get judged on wins and losses,'' he said. "But I'm very optimistic about this season.''