PITTSBURGH (AP) – Pittsburgh Steelers quarterback Ben Roethlisberger not only doesn’t have a serious knee injury, as the team initially feared Monday night in San Diego, he could play again as early as Sunday.

After an eventful 24 hours in which the Steelers rallied to win 24-22 after blowing a 14-point lead, lost their star quarterback to what looked to be a frightful injury, and flew all night, coach Bill Cowher was more relieved than happy. And he was very happy.

Roethlisberger sustained a hyperextended left knee and a bone bruise after being struck by Chargers defensive end Luis Castillo’s helmet with 1:05 remaining in the game – but nothing else. No ligament tears, no tendon or cartilage damage, all of which the Steelers feared after Roethlisberger was removed from the field by a cart.

“I think we’ll all have a deep sigh of relief in regards to the diagnosis,” Cowher said Tuesday after Roethlisberger had an MRI exam not long after getting off the plane from California.

“I guess the dire situation we thought we had coming in here this morning doesn’t appear to be that right now.”

When they left the field Monday night, some Steelers players were contemplating what it would be like if they needed to play weeks, if not months, without the quarterback who is 16-1 as an NFL starter.

Another cause for worry was that backup quarterback Tommy Maddox, the starter at the beginning of the 2004 season, sat out Monday with a calf injury that occurred Friday in practice.

But there was a favorable medical report on Maddox, too; instead of being out 3-4 weeks, he could be ready as soon as Sunday, too. Still, to protect themselves, the Steelers signed former Pitt and Carolina Panthers quarterback Rod Rutherford to their practice squad.

Despite the much better than expected medical news, it seems unlikely the Steelers (3-1) would rush back Roethlisberger to play Sunday against Jacksonville (3-2), especially after a short week of preparation.

For now, Cowher said, “Charlie Batch is the starter by default until I see more. … We’ll see how the week progresses.”

Batch, the Lions’ starter from 1998-2001, has thrown only eight passes in four seasons since signing with his hometown Steelers, and the team debated whether to keep him at the end of training camp. But he secured his roster spot by throwing two touchdown passes in the final exhibition game against Carolina on Sept. 1, and Cowher is thankful the team kept a third veteran quarterback – something most NFL teams don’t do.

“It probably seemed a bit of a luxury,” Cowher said. “But there’s a lot to be said for having veteran guys who have lined up and won games in the National Football League, who have won playoff games.”

Also undecided is whether running back Jerome Bettis or Willie Parker will start against the Jaguars.

Parker has been held to 81 yards in two games since running for more than 100 yards in each of the first two games, and he was replaced for much of the second half Monday by Bettis.

Bettis, playing for the first time since injuring a calf during the third of the four preseason games, carried seven times in the 10 plays that led to Jeff Reed’s decisive 40-yard field goal with 6 seconds remaining. He finished with 54 yards on 17 carries and a touchdown.

For now, 2004 starter Duce Staley appears out of the picture because of a training camp knee injury that, Cowher said, “May not be 100 percent all year.” Bettis moved ahead of Staley on the depth chart during practice late last week.

“Jerome Bettis, he gives you something,” Cowher said. “He’s a very special back. … You see him running and jumping and jump-cutting, doing the things that he does.”

The only Steelers player currently ruled out of Sunday’s game is cornerback Ricardo Colclough (shoulder).

AP-ES-10-11-05 1828EDT