Derek Jeter crumpled to the dirt, his season suddenly over and his future uncertain.

New York’s pennant hopes faded quickly after the star shortstop broke his ankle last October, and the offseason wasn’t much easier for the Yankees, with Jeter and his team forced into a tense recovery process that still isn’t over.

“Our big thing is not to have any setbacks now,” Manager Joe Girardi said recently. “But it’s really nice to see him on the field.”

For Jeter and the Yankees, the April 1 season opener against Boston is looking more like a deadline than a day of anticipation. Jeter insists he’ll be in the lineup that afternoon, but teammate Alex Rodriguez has no chance. Then there’s closer Mariano Rivera, who is recovering from a major injury of his own after hurting his knee last May.

And the Yankees are just one club with the injury bug. All around baseball, division races may be decided not by offseason moves or midsummer surprises — but by how well teams can keep their top players on the field.

Trying to handicap the NL West race between the World Series champion Giants and the new-look Dodgers? A lot depends on how healthy Carl Crawford is, and whether he can rediscover the form that made him a star left fielder.

Think Detroit is a lock to win the AL Central? What if Victor Martinez can’t rebound from his knee injury and the Tigers go the whole season without a productive designated hitter?

What about all the changes in Toronto? The Blue Jays could be much improved — assuming Jose Bautista is fully recovered from wrist surgery.

“All the exercises and rehab and stuff like that have come and gone, and I’ve been working my butt off to make sure I was ready to go when the season started,” Bautista said.

Any discussion of injury worries should begin with the Yankees, who lost Jeter to a broken left ankle in the AL Championship Series opener against Detroit. The Yankees went on to lose to the Tigers in four straight games, and Jeter endured what he described as a “terrible” offseason.

He’s been able to take part in spring-training workouts, but his first exhibition game is probably a couple weeks away.

The Yankees won 95 games last year despite losing Rivera to a torn anterior cruciate ligament in his right knee. He’s expected to be ready by opening day. Ace left-hander CC Sabathia also is on the mend. Sabathia is coming off arthroscopic surgery in October to remove a bone spur from his left elbow.

Meanwhile, Rodriguez isn’t even at spring training. His rehabilitation from hip surgery is taking place primarily in New York, and the third baseman is expected to be sidelined until at least the All-Star break.

The Yankees hope to be as close to full strength as possible in a wide open American League. Detroit won the pennant last year, even though Martinez missed the whole season because of a left knee injury.

The Tigers are glad to have the upbeat Martinez back in the clubhouse and true to form, he found a bright side to his lost season.

“This year was weird but at the end I’m going to tell you: It was the best year of my life,” Martinez said.

“I got the time that I never had before to spend with my family, my kids. I was able to go to bed and wake up with them every single day. I don’t think anything’s going to beat that.”

Still, watching the Tigers play on without him was difficult. In that respect, Martinez can relate a bit to what Baltimore’s Brian Roberts went through.

Roberts has been with the Orioles his whole big league career but when the team finally made the playoffs in 2012, he’d had season-ending hip surgery in August. After another operation for a sports hernia in December, it uncertain whether the second baseman’s body can hold up.

“I just need to play. That’s going to be the biggest thing, to just get out there,” Roberts said.

No matter what a team did during the offseason, a significant injury can ruin the best of plans. The Blue Jays look like contenders in the AL East after acquiring Jose Reyes and R.A. Dickey, but Bautista was limited by those left wrist problems last year, hitting only 27 home runs after slugging 97 over the previous two seasons.

Atlanta was among the biggest newsmakers in the National League, signing B.J. Upton and trading for his brother, Justin. But there’s still a question mark at catcher because Brian McCann is returning from surgery to repair a torn labrum in his right shoulder.

Johan Santana of the Mets missed a year following shoulder surgery in September 2010, and although he looked plenty healthy last June 1 when he threw the first no-hitter in Mets history, his season ended in August because of ankle and back problems.

“What’s important right now is to stay healthy,” Santana said. “As far as numbers and all that, if I’m healthy and I’m there, I have a good chance to put up those numbers.”