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05/03/2013 6:34 PM ET

Rivera amazes one year after knee injury

NEW YORK -- The calendar indicates a full year has passed since Mariano Rivera crumpled to a Kansas City warning track after stumbling in pursuit of a batting-practice fly ball, his right anterior cruciate ligament torn and his baseball future in serious doubt.

One day later, after a night of quiet reflection and soul-searching in his hotel room, Rivera hobbled into the visiting clubhouse of Kauffman Stadium and vowed, "I am coming back. Put it down. Write it down in big letters. I'm not going down like this."

Months of intensive, grueling rehabilitation followed, and as Rivera worked his knee back into the shape necessary to handle a big league pitching regimen, the future Hall of Famer acknowledged that there were moments of doubt in which he wondered if he would actually make it back.

But his surgically repaired knee passed every winter test, breezed through a Spring Training workload with no issues, and the 43-year-old all-time saves leader hasn't seemed to skip a beat as he started his final Major League season a perfect 11-for-11 in save opportunities.

"I said all along that it wasn't his arm, so I wasn't really concerned about the type of stuff that we would see from Mo," Yankees manager Joe Girardi said. "Maybe the most amazing thing about Mo is that he's still doing it at his age.

"But he's been consistent his whole career. He's had the same mentality his whole career. But to be doing it at his age is really incredible."

In a way, it is because Rivera fell while chasing Jayson Nix's outfield drive on the afternoon of May 3, 2012, that he has been able to enjoy a farewell tour throughout the big leagues. Rivera said this spring that he had decided '12 would be his final season, a fact he had dropped hints about but had not been ready to officially reveal at the time.

Rivera made sure no one had any doubts this spring, announcing his intention to call it a career in a March 9 news conference in Tampa, Fla., saying that his tank was nearly empty and he intended to fully exhaust those last few drops on the diamond this year.

"If I would have finished the season last year, I would have retired last year, definitely," Rivera said. "I didn't want to leave like that. I felt like I wanted to give everything and I still had something left. This year, I knew what I wanted to do."

Yanks bring up Claiborne to bolster 'pen

NEW YORK -- The Yankees purchased the contract of right-handed reliever Preston Claiborne on Friday from Triple-A Scranton/Wilkes-Barre, and the rookie shouldn't be surprised if he is asked to get a few important outs quickly.

Because right-hander David Robertson is expected to be sidelined until Tuesday at Colorado with a sore left hamstring, the Yankees may not have much time to ease in Claiborne, a 25-year-old who is replacing the injured Joba Chamberlain on the active roster.

"We'll just have to mix and match a little bit more," Girardi said. "Usually when we bring Joba and Robby in, it's pretty strict. They're going to see whatever they're going to see. But we'll probably have to mix and match a little more until we get Robby back."

Claiborne had three saves in three chances at Scranton/Wilkes-Barre, where he posted a 3.48 ERA in eight outings, allowing four earned runs and 14 hits in 10 1/3 innings while walking one and striking out 10.

In order to make room on the 40-man roster for Claiborne, the Yankees designated right-hander Cody Eppley for assignment.

Girardi said that Shawn Kelley could also see increased duty in the late innings, but he saw this spring that Claiborne was consistent with his stuff and didn't look overwhelmed, compiling an 0.84 ERA in 10 appearances.

As for Claiborne's scouting report, Girardi said that he features a swing-and-miss slider, a decent changeup and a fastball that gets up to 95 mph. Claiborne was thrilled to get word of the promotion from Triple-A manager Dave Miley, and he is hoping to make a quick impression.

"It's always a different animal coming from Triple-A and pitching against guys up here," Claiborne said. "Obviously I don't have the extended experience pitching at this level, but pitching in Spring Training and getting a little taste of what it's like and what veteran hitters are like, having that limited experience is definitely beneficial."

Nelson looking forward to opportunity with Yanks

NEW YORK -- Chris Nelson said that he is looking forward to a new opportunity after being acquired by the Yankees from the Rockies late on Wednesday evening.

"I was excited. I was sad to leave Colorado, but this is the next chapter of my life," Nelson said on Friday at Yankee Stadium.

Nelson, 27, was obtained in exchange for cash considerations or a player to be named.

He will be asked to provide the injury-depleted Yankees with some depth behind Jayson Nix at third base and Robinson Cano at second base. The right-handed hitting Nelson said that he is comfortable at both positions.

"He's going to play some third. He's played second as well in his career," Yankees manager Joe Girardi said. "I know he was drafted as a shortstop, but probably mostly third for him. We'll get him involved in the mix. I think we're going to see some left-handers next week, too."

A first-round Draft pick of the Rockies in 2004, Nelson batted .242 (16-for-66) with four RBIs in 21 games for Colorado before he was designated for assignment on April 28 so the Rockies could make room for prospect Nolan Arenado on the active roster.

"It was kind of a competition in Spring Training," Nelson said. "I won the job in Spring Training and kind of knew something was going to happen within the next couple of months. It happened a little earlier than I thought."

Bombers bits

• Robertson had an MRI on his left knee during Thursday's off-day and, while the right-hander is listed as day to day, Girardi said that he did not expect to use Robertson until Tuesday in Colorado.

• Mark Teixeira had a third day of tee-and-toss in the indoor batting cages at Yankee Stadium on Friday and is hoping to progress to on-field batting practice by the end of the weekend. Teixeira is expected to travel to Tampa after Sunday's game and is hopeful that he will be able to rejoin the big league roster by June 1.

• Cano made his Major League debut on this date in 2005 at Tampa Bay, going 0-for-3. Cano has played more active games as a Yankee (1,241) than the other 12 position players currently on New York's roster combined (1,074).

• Friday marked Girardi's 1,000th game as a Major League manager. He entered play holding a lifetime record of 574-425 (.575) in seven career managerial seasons, including his 78-84 season with the Marlins in 2006.

Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.