Derek Jeter and the Yankees believe the shortstop will be ready for Opening Day against the Red Sox on April 1. That’s the plan for Mariano Rivera, too. Yet, until Joe Girardi experiences Jeter and Rivera doing everything on the field without setbacks, there will be some doubt in the manager’s mind. “You want to see [Jeter] and get over that, ‘I am done worrying about him,’ ” Girardi said. “The same with Mo: ‘I am done worrying about him.’ ’’ Jeter is coming back from a fractured left ankle suffered in the ALCS against the Tigers, and Rivera missed five months with a torn ACL in the right knee. “I would be more worried about Mo if it was his arm instead of the knee,’’ Girardi said of the 43-year-old closer. “I don’t think it will affect his pitching. If it was a shoulder or elbow, I would be more concerned.’’ * CC Sabathia, who had bone spurs removed from the left elbow in October, will throw a bullpen session tomorrow. He will be limited to fastballs and changeups and not throw breaking pitches. Sabathia was on the DL twice last season with elbow problems and has noticed a difference playing catch. “I have better range of motion and not achy at the end of the extension,’’ said Sabathia, who reported at 290 pounds, the same weight he was at the start of camp last year and 10 pounds lighter than he was at the end of last season. * When the Yankees open the season they will be without 112 homers from a year ago, forcing Girardi’s lineup to play differently. “I anticipate it will be different because we don’t have the home run hitters we have had in the past, so we are going to have to find different ways to score runs,’’ Girardi said. “When you look at our club this year, there is more speed [with Brett Gardner]. I think our offense is going to be different, but I believe that we are going to score runs. It’s going to be in a different fashion.’’