After a poor game to start the season, Tony Romo drew admiration for playing with a broken rib against the 49ers. (Charlie Neibergall/Associated Press)

If it’s possible for a team to have a roller-coaster season in only two games, the Dallas Cowboys might qualify.

The low point already has been unusually low and the high point unusually high for the Cowboys and their quarterback, Tony Romo, in particular.

The Cowboys kept their season from turning into another early nightmare when they rallied to win in overtime Sunday in San Francisco, where Romo returned from a fractured rib on the team’s first offensive series to engineer the triumph.

That came a week after a deflating season-opening defeat on the road to the New York Jets, which Romo said he had lost single-handedly with a late fumble and an interception. His crunch time failure reignited the debate about whether Romo’s game is sufficiently polished for him to be a consistent winner in the NFL.

Cowboys Coach Jason Garrett, like many NFL coaches, likes to preach to his players that they have 24 hours to set aside the emotions of any game, good or bad, and move on to the preparations for the next game. That probably has been easier said than done for the Cowboys. But as they ready for Monday night’s game at home against the Washington Redskins, the Cowboys at least could return to work this week feeling positive about themselves after their 27-24 victory over the 49ers.

“We talk about it all the time: It’s one play at a time. It’s one game at a time,” Garrett said at a news conference Monday after his second game as permanent head coach. “Keep going forward regardless of what the previous result was. Be able to handle adversity. Be able to handle success. . . It’s probably no more important [for any other player] than at the quarterback position.”

It was a relatively quiet preseason for the Cowboys, even after Garrett led them to a 5-3 second-half record in 2010 as interim coach, after taking over when Wade Phillips was fired following a 1-7 start. The Super Bowl talk that surrounded the Cowboys last season, with the game set to be played on their home field, was gone as this season neared. The Philadelphia Eagles drew the most attention among NFC East teams for their post-lockout shopping spree.

But the spotlight quickly has found Romo again in his return from the broken collarbone that caused him to miss most of last season. He played brilliantly for most of the opener, carving up the Jets’ defense as the Cowboys built a 24-10 fourth-quarter lead. But then came a fumble on a scramble at the New York 3-yard line and an interception on a pass thrown directly to cornerback Darrelle Revis to set up the game-winning field goal for the Jets.

Romo faced an onslaught of analysis by media who asserted that he made too many mistakes late in games to be regarded as a reliable quarterback. Owner Jerry Jones defended Romo. But on Sunday, Romo was hurt and the Cowboys fell behind, 14-0. Garrett went to backup Jon Kitna for most of the third quarter.

Then Romo tapped Garrett on the shoulder and said he was ready to return to the game. The Cowboys got a tying field goal at the end of regulation and Romo threw a 77-yard pass to wide receiver Jesse Holley in overtime to set up the winning field goal.

“It’s a challenging position every week,” Garrett said Monday. “It’s certainly challenging when you have a fractured rib. . . . I think it was physically painful for him. He was getting sick, too. He was nauseous. . . . I just knew at some point I was going to get a tap on my shoulder and it was going to be him wanting to go back in. And I’m glad he did.”

Romo said he had learned from his late mistakes against the Jets and the scrutiny that followed, and he relished the chance to have the ball back in his hands with the game on the line against the 49ers.

“We live in a world that it’s all about this week and we’re going to make all our assumptions and base all of our opinions about that,” Romo said at his postgame news conference Sunday. “That’s part of the fun of sports is that now all of a sudden we can all say what we think because you won or you lost. I just keep going along and playing and getting better each year.. . . If you do that, eventually you’ll have a great chance to achieve the goals that you’ve set out.”

Tests also showed evidence that Romo had suffered a collapsed lung, the Cowboys announced Monday. Garrett gave his players an extra day off as part of their longer work week. But he said there’s no reason to believe that Romo won’t play against the Redskins. The Cowboys also are likely to have tailback Felix Jones in the lineup despite a shoulder injury, but probably will be without wide receiver Miles Austin, who aggravated a hamstring injury.

Garrett formerly was the Cowboys backup quarterback, behind Hall of Famer Troy Aikman. He said Romo’s exploits Sunday reminded him of things that Aikman once did.

“They have a lot of similar traits that way,” Garrett said. “They’re great competitors. They’re incredibly tough physically and incredibly tough mentally. There’s not a lot of conversation that goes on with either of them. It’s just, ‘I’m playing.’ ”