Tony Romo is Dallas’ “Comeback King”…

The 34-year-old Mexican American NFL quarterback stayed cool, calm and collected in the late stretch to help lead his Dallas Cowboys to a massive come-from-behind win against the St. Louis Rams.

“No one ever comes that wide open,” Romo said of his 68-yard touchdown pass to Dez Bryant that was among the big plays that helped the Cowboys erase a 21-0 deficit and stun the Rams 34-31 on Sunday. “You want to make sure you don’t do anything stupid.”

Romo’s impressive performance down the stretch help the team match its biggest comeback in franchise history, and helped give him his own franchise best record.

The Cowboys (2-1) had plenty of time to chip away, and no one panicked about the cushion they’d spotted the Rams.

“We never blinked, I can honestly say that,” Bryant said.

Romo has 21 comeback victories in the fourth quarter or overtime, a franchise best.

“Tony went out there and did what Tony do,” Bryant said. “He was poised and he knew what he wanted to do.”

Terrance Williams scored the go-ahead touchdown late in the fourth quarter, and Bruce Carter returned an interception 25 yards for a TD on the next snap, capping the rally.

DeMarco Murray‘s 1-yard run late in the first half began the comeback.

Dallas also rallied from a 21-point deficit in 1984 against the New Orleans Saints and 1999 against the Washington Redskins, although both of those wins came in overtime.

It tied the second-largest lead blown by the Rams (1-2), who slowed Murray but got burned everywhere else. Among other breakdowns was a flubbed snap by center Scott Wells, who didn’t realize Austin Davis was in the shotgun, resulting in a lost fumble, and a. They settled for a field goal.

“I feel like I let this game slip through my hands and it’s my fault,” said Jared Cook, who dropped a touchdown pass that could have put the Rams up 28-21

Romo was 4 for 5 for 40 yards and scrambled 16 yards on third-and-13 on the go-ahead drive. His second-half play overshadowed a third costly INT of the year.

“We were able to execute under pressure or whatever you want to say, blah, blah, blah,” Romo said. “We got it done.”