KISSIMMEE, Fla. -- Call it the Yankees' "Break in case of emergency" plan. Should Mariano Rivera be sidelined for a significant period of time, right-hander Joba Chamberlain appears to be the man behind the protective glass.

Rivera has come back strong following arthroscopic right shoulder surgery over the offseason, but the New York Post reported on Wednesday -- citing three Yankees officials -- that the Yankees would likely look to Chamberlain as their contingency plan for the closer's role should Rivera suffer any significant setback.

Chamberlain, a setup reliever upon his arrival to the Major Leagues in 2007 and for about half of last season, is expected to continue as a starter. But the officials told the Post that the subject of who would replace an injured Rivera has been discussed at the highest levels, and the belief is that Chamberlain would be the best-suited replacement.

Chamberlain, 23, recently said that he has accepted the fact that he may never be free of the debate concerning how best to use his talents, which continues to rage on sports-talk radio and among fans.

"It's like anything -- if I mess up in the bullpen, they'll say I should have been a starter and if I'm a starter, they'll say that I should be back in the bullpen," Chamberlain told MLB.com.

"It's kind of six of one and a half-dozen of the other. It's going to be a debate for a while. I'm going to have a bad start and everyone is going to say I should go back to the 'pen. It's going to be one of those things that's probably going to be talked about for a while."

According to the Post, Chamberlain would be the top choice because of his combination of temperament, pitching skills and ability to handle the high-pressure job of Yankees closer -- especially one taking the place of the legendary Rivera.

Right-hander Brian Bruney and left-hander Damaso Marte are expected to be manager Joe Girardi's leading options to set up for Rivera, and Bruney is considered the only other Yankees reliever who could possibly be given the chance to close in the event of an extended absence by Rivera. But one Yankees official, referring to Bruney, told the Post, "Let's see him handle the eighth inning first."

The 39-year-old Rivera made his first appearance in an exhibition game on Tuesday, pitching a perfect fifth inning against the Pirates, striking out two and inducing a weak ground ball to the mound.

Showing no signs of pain from the protruding AC joint he had shaved in his pitching shoulder over the offseason, Rivera needed just 11 pitches -- of which eight were strikes -- to retire three batters.

"I had no doubt about that," Rivera said. "It's a matter of going there and making sure everything is OK, that you do all of your things right. That's what I did today."

Chamberlain took the league by storm when he first reached the Majors. He was moved into the setup role, displacing an ineffective Kyle Farnsworth, and allowed only one earned run and 12 hits while striking out 34 in 24 innings.

Chamberlain was 4-3 with a 2.60 ERA in 42 appearances (12 starts) last season, continuing in the setup role for the first two months before transitioning into the rotation. He made his first Major League start on June 3 and went 3-1 with a 2.76 ERA as a starter before rotator cuff tendinitis forced him to the disabled list. He returned to make 10 relief appearances in September.

Asked this spring once and for all about his preference of starting or relieving, Chamberlain answered, "To win a ring."

"I don't really care," Chamberlain continued. "I love both roles, and they're two totally different roles. But at the same time, you attack people the same way and you get to pitch."