SAN FRANCISCO -- Cowboys quarterback Tony Romo fractured a rib in the first half of Sunday's game against San Francisco but returned for the final drive of the third quarter with his team trailing 21-14.

The Cowboys eventually rallied during the fourth quarter and won, 27-24, on a field goal during overtime.

A source told ESPN's Ed Werder the team believes Romo fractured two different ribs. Romo will undergo a CT scan Monday, the source said.

Romo came back moments after the team announced he had a broken rib and wouldn't return. He was clearly uncomfortable, grimacing at times.

In the end, Romo hit Jesse Holley on a 77-yard completion on the Cowboys'

first play of overtime that set up Dan Bailey's winning 19-yard

field goal.

"It's got to be one of those things that will follow him

through his career. I know what it was here in the locker room at

halftime. I know what he had to do to get back on the field,"

Cowboys owner Jerry Jones said.

"I know what he had to do before (painkillers) took hold to

relieve him from his pain. But, boy, did he come back. That was

inspirational."

Romo, who completed 20 of 33 passes for 345 yards in the win, didn't take a pain-killing injection or wearing any equipment to protect the injured area, sources told Werder.

"Ribs are tough," Romo said. "It's just hard to breathe, and

talk really. You have to talk loud, especially on the road."

Jon Kitna replaced Romo at the start of the third quarter, throwing two interceptions and a 5-yard touchdown pass to Miles Austin.

Romo came out of the locker room after the second-half kickoff and walked onto the field briefly as Kitna returned to the sideline, then Romo came off and later returned slowly to the locker room. He kicked the ground in frustration.

Back on the sideline late in the third quarter, Romo tapped

Jason Garrett on the shoulder and told the coach to put him back in

the game.

"Eventually, what was convincing was, 'At some point I'm going

to play with this thing, so why not now?' " Garrett said, quoting

Romo. "It's about a quarterback but it's really about a football

player and a competitor. And Tony is that. One of the best

competitors I've ever been around."

Romo said: "I just told him I was good to go. I think he asked some of the

guys. I didn't give him too much of a chance. I just

ran on the field."

Romo played through multiple hits in the first half, when he threw a late 53-yard TD pass to Austin to bring Dallas within 14-7.

Romo came up slowly after being hit on a blindside cornerback blitz by Carlos Rogers as he was throwing in the second quarter.

Romo, who said this week he would come out and play his "best game" after blowing a 14-point lead last Sunday night against the Jets, went 8 for 17 for 144 yards and the TD before leaving the game.

Information from The Associated Press was used in this report.