NEW YORK -- Phil Hughes found a safe place to stash the game ball and lineup card from his first Major League save this week, tucking the keepsakes deep in the recesses of his Yankee Stadium locker.

The right-hander doesn't know how many more opportunities will be coming down the road, but he is prepared to keep helping the Yankees in this new role. One thing seems certain: Mariano Rivera needn't worry about Hughes creeping up on his career saves total.

"I'll only need, what, 500 and whatever more?" Hughes said, with a laugh.

Rivera has 510 saves, and Hughes was just keeping the closer's spot warm on Thursday as he recorded the final six outs of the Yankees' 6-3 victory over the A's.

Hughes' place is more in a setup role for Rivera, and he has excelled. The 23-year-old now owns a 0.74 ERA in 17 relief appearances, averaging more than a strikeout per inning, and his emergence has proved invaluable.

"He was one of the best arms that we had and some of the better stuff that we had in our organization," Yankees manager Joe Girardi said. "We thought he would pitch some important innings for us and give us some depth in the bullpen. We weren't sure he'd evolve into what he's evolved into right now. He has changed our mind in the way that we use him."

Girardi said that the original plan was to use Hughes in much the fashion that the Yankees utilize Alfredo Aceves, keeping a long man in the bullpen capable of throwing 50 to 60 pitches on an occasional basis.

But that plan changed as Hughes was been converted into a full-fledged reliever, helping to patch a hole left by injuries to the original envisioned eighth-inning men, Brian Bruney and Damaso Marte.

Hughes has excelled in the assignment, not permitting a run in his past 15 outings since June 14 to compile 19 2/3 scoreless innings entering play Saturday.

"I just basically take it an inning at a time," Hughes said. "You've got to go out there and expect to shut down every inning. Obviously, I'm going to give up runs; that's part of being a pitcher. But right now, we're winning games and I'll try to keep it going as long as I can."

According to the Elias Sports Bureau, Hughes' string is the longest single-season scoreless stretch for a reliever since Mariano Rivera compiled 23 straight innings in 2005.

"It's still the same ballpark, still the same hitters," Hughes said. "The outs are the same outs to get, the same strikes. It's really not different. I just go out and throw strikes and keep it as simple as possible."

Because Hughes has shown signs of becoming a more polished Major League pitcher, the Yankees still envision him as a starter in the future and have not ruled out the idea that he could return to the rotation as early as this season.

But with the Yankees leading the American League East and having found a solution for the elusive "Bridge to Rivera," Hughes might just as easily stay right where he is.

"You're not sure what's going to happen to your club. But if the club was to stay the same, there's a shot he would remain in the bullpen for the rest of the year," Girardi said.

"... I wouldn't say that he will not start a game for the rest of the year, but I can't tell you that he will, either."

General manager Brian Cashman said this week that Hughes would be one of the internal options to join the rotation in the event of an injury, though he acknowledged it would be quicker to build Aceves up to the necessary pitch count.

That knowledge is comforting for Hughes, who appears to have found a home working in the late innings.

"It would take some time for me to get stretched out as a starter," Hughes said. "I'm just glad I don't have to worry about it. I can just go out and pitch."