Chicago ? Rex Grossman had spent too many hours in rehab, in film sessions and on the practice field for the unthinkable to happen again. But his expression of disgust and disbelief as he was wheeled off the field said it all.

Grossman broke his left ankle Friday night in St. Louis, the second major injury for the Chicago Bears’ promising but still unproven quarterback in as many seasons. He’ll be out three to four months, which just about washes out the season.

The optimism that had been flowing since the Bears began camp last month was doused by the sight of Grossman leaving the field.

“It’s not really going to do me any good to be angry,” said Grossman, the Bears’ first-round pick in 2003.

“All I can do is be positive and know that I’ve got another tough challenge in front of me. I’m going to get healthy. I’m just a positive person and I feel like this is another bad thing that happened, but I know great things are going to happen for me.

“I can just feel it. I feel like I’ve been through hell and I’m going to come out of it.”

Grossman waited his turn as a rookie as Kordell Stewart and Chris Chandler started. He started the final three games and played decently but suffered a tendon injury in his right hand that forced him out of the season finale at Kansas City.

Grossman helped Chicago to a victory at Green Bay in the second week a year ago, but in Game 3 he was knocked out for the season after tearing a ligament in his knee at Minnesota.

In his absence, the Bears finished 5-11 while turning into the worst offense in the NFL, using backups Jonathan Quinn and Craig Krenzel before finally turning to Chad Hutchinson, signed when Grossman was hurt.

Now Hutchinson is No. 1 again – he started nine game for the Cowboys in 2002 and was 1-4 for Chicago a year ago.

That’s the way things have gone in this dismal era for the Bears, who have had nine different starters at quarterback since 2000, beginning with Cade McNown, a first-round pick in 1999 who never made it. The others range from journeymen like Stewart, Chandler, Shane Matthews and Jim Miller to the oh-so-green Krenzel last season.

Grossman had spent long hours getting healthy and just as many learning Turner’s offense – his third different system in as many years- while developing a relationship with new receiver Muhsin Muhammad. They clicked so well that Grossman invited Muhammad to his wedding this summer.

Now Grossman will have to wait again to show what he can do. The former Florida star, a runner-up in the Heisman Trophy balloting, will be rehabbing instead of throwing passes, a situation he could never have envisioned reliving again so soon.

Grossman had been flushed from the pocket by Jeremy Loyd and Trev Faulk and then spun and dropped by Faulk, initially getting back to his feet before slumping to the turf and grabbing his left knee in pain.

For the second straight season, he was injured on a turf field.

“I knew right away and I was kind of in denial to start with,” he said.

“I tried to walk it off, but I heard a pop and I tried to make it work, but I knew when it happened. I was caught in one of those situations where someone kind of twisted me and sat on my leg and you know, what are you going to do?”