Mariano Rivera warms up his arm at George Steinbrenner Field...

Mariano Rivera warms up his arm at George Steinbrenner Field during spring training in Tampa, Fla. (Feb. 14, 2013) Credit: Newsday/J. Conrad Williams, Jr.

TAMPA, Fla. -- As CC Sabathia walked past the back bullpen at Steinbrenner Field Saturday morning, on his way to stretch before a throwing session there, he glanced to his right, where another pitcher was popping a catcher's mitt.

"Why is Mo already throwing?" he asked Andy Pettitte.

On the original schedule for Saturday, Sabathia, Pettitte and Mariano Rivera were scheduled to throw their bullpen sessions at 9:50 a.m.

But in response to Sabathia's question, bullpen coach Mike Harkey said with a smile: "Mo wanted to throw alone."

Rivera for years has been the one most responsible for his own spring training schedule -- with the Yankees' full blessing -- and this was another alteration.

But Sabathia's question, though not his intent, easily could have had a second meaning.

In recent years, Rivera's first bullpen session typically hasn't taken place until a week or more into camp. But this marked his second since camp opened Wednesday.

The reason, Rivera said this past week, is his surgically repaired right knee. Because he is coming off an ACL tear, Rivera, who is wearing a light brace on the knee, said his workload needs to be increased to make sure he is ready for the regular season.

"Everything was good. Perfect," Rivera said after throwing 25 pitches to bullpen catcher Roman Rodriguez.

Said Rodriguez: "Same guy. No difference."

Joe Girardi did not watch the session, but the reports he received from pitching coach Larry Rothschild were encouraging.

"It was good," Rothschild said. "I don't know what you say about him anymore."

Of course, two good bullpen sessions don't necessarily portend the kind of season Yankees fans have long expected out of Rivera. But it beats the alternative.

"I trust myself," said Rivera, who compared the brace to a "sock" that he hardly knows is there. "I trust God first and I trust myself that I'm capable of doing this. I was expecting this. It feels good. Everything feels good."

Rivera, 43, baseball's all-time leader in saves (608), will throw again Tuesday. He said bullpen sessions are one thing and that the significant hurdles will be when the action really counts.

"If I'm looking for something, it's the games," Rivera said. "The reason why is because you have to react there. Comebackers, covering first, all that stuff. You can't think, you have to react. That, I would say, will be the biggest test."

Sabathia, meanwhile, tested his left elbow with 29 pitches in his first bullpen session. The lefthander had offseason surgery to remove a bone spur, and the Yankees already have said they will take things slowly with their ace.

The exhibition season starts Saturday. Sabathia will not take a turn in the rotation the first time through and is unlikely to start a game until the week of March 4, Girardi said.

Sabathia said his arm feels good and that he has had no setbacks. He said he was a little "nervous" about his bullpen session, but only because he had not been on a mound in a while.

"No problems," said Sabathia, who threw all fastballs and changeups, which is typical for him this early in spring training. "Probably didn't throw a strike, but that's normal for my first bullpen. But it's exciting to get back out there on the mound. I felt good and felt comfortable after the first couple of pitches."

Girardi said having his ace and closer both coming off surgery in and of itself doesn't concern him, but he's still taking a pragmatic approach.

"I'm pretty confident they're going to be OK," he said. "But I always say in the back of my head, I want to see them out there before I make that assumption.

"I feel pretty good because I know where they are in their rehabs, I think they're pretty far along. They've had good winters. Mo's been throwing for a while. I feel pretty good about it, but I want to see Mo in a game having to break to first. I want to see that."

SUBSCRIBE

Unlimited Digital AccessOnly 25¢for 6 months

ACT NOWSALE ENDS SOON | CANCEL ANYTIME