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6/2/2014 6:48 P.M. ET

CC encouraged by progress in knee therapy

NEW YORK -- In a batting cage underneath Yankee Stadium's first-base seats, CC Sabathia did a little multi-tasking on Monday afternoon. Seated in a chair, Sabathia gave his arm a workout, tossing batting practice to his 11-year-old son.

Sabathia is still a long way from facing big league hitters, but the left-hander feels as though he is making progress in recovering from a stem-cell injection intended to assist a breakdown of cartilage in his right knee.

"It's really day to day," said Sabathia, who has advanced from underwater therapy to a treadmill. "I'm taking it further each day with more stuff and seeing if it's going to swell up. I have no pain so far, so we start throwing sometime this week, and we'll go from there."

The Yankees have said that Sabathia is unlikely to return before July. Sabathia said that he will feel more at ease about his situation when he plays catch outdoors, standing up.

"I feel great right now. I do feel pretty confident," Sabathia said. "I didn't know going into it -- I woke up, my leg was stiff, and I didn't know what was going on. But three, four days later I felt pretty good, and I've been feeling good ever since."

Sabathia said that he reached out to the Knicks' Amar'e Stoudemire about the injury. Stoudemire had a similar stem cell procedure in 2005, when he was with the Phoenix Suns.

"I talked to Stat a lot about it; he had some knee procedures done, and had done the stem cell thing, too," Sabathia said. "We talked a lot about it. He gave me some advice, some exercises to do, and it helped out a little bit."

Injured Beltran, Cervelli continue to progress

CLEARWATER, Fla. -- Injured Yankees Carlos Beltran and Francisco Cervelli each played three innings in an extended spring game at the Phillies' Carpenter Complex on Monday.

Beltran, who hasn't played since May 12 due to a bone spur in his right elbow, went 0-for-3 as the club's designated hitter. Cervelli caught three innings behind the plate and went 1-for-2 with a double and a walk.

Beltran, 37, had been taking batting practice at Yankee Stadium before traveling to Florida. He said his plan is to play in two more extended spring games and, if everything goes well, join the Yankees on a 10-game road trip that begins on Friday in Kansas City.

"I feel good, man," Beltran said. "The elbow felt good. That's the reason why I'm here, to try to test it. Today, three at-bats; [Tuesday] hopefully a little more. As soon as I do all these days here and everything goes well, then I'll go back."

Beltran said he has just been hitting, not throwing, which means he likely will be limited to being the Yankees' DH upon his return.

Beltran has hit .234/.286/.430 with five homers and 15 RBIs in 33 games this season. He has had two cortisone injections in his injured elbow, and he may have to undergo surgery at some point.

"The plan is hopefully I finish the season, stay healthy, and then when the season is over, I'll address that issue," Beltran said.

Cervelli, meanwhile, said that Monday's workout marked his third extended spring game. The 28-year-old catcher hasn't played since April 13 due to a right hamstring strain, and he was placed on the 60-day disabled list on April 15, retroactive to April 14.

Cervelli said he has been slowly ramping up his rehab because he's about two weeks from being eligible to return, but his leg has felt "very good" and is "getting stronger."

"Very good," Cervelli said. "We're going slow because I've got two more weeks, so I had to wait. But we're doing good."

Cervelli expects to spend a few more days in extended spring camp before joining one of the Yankees' Minor League affiliates for more rehab games. He has been encouraged by his progress so far, however, and is eager to get back to New York.

"Can't wait," Cervelli said.

Dominant Betances drawing comparisons to Mo

NEW YORK -- The comparison has been made several times by voices around the team this season, and it is a great compliment that it seems appropriate. Dellin Betances may wind up being just as electric for the 2014 Yankees as Mariano Rivera was for the World Series-winning 1996 squad.

Betances has been nothing short of dominant this season, racking up another five strikeouts in two perfect innings of relief Sunday. He is allowing just 6.61 baserunners per nine innings entering play on Monday, the second-best mark in the American League and the fourth-best in the Majors.

At 6 feet 8 inches, Betances is more physically imposing than Rivera was during that banner, breakout year as John Wetteland's setup man, and arguably just as impressive. Rivera was 8-3 with a 2.09 ERA in 61 regular-season appearances in '96, striking out 130 and walking 34 in 107 2/3 innings.

"I think you can look at the numbers and they're probably fairly comparable," Yankees manager Joe Girardi said. "[Rivera] was a guy that we would use for multiple innings, and he was extremely effective, just like Dellin has been. So I can understand the comparisons. Obviously they're different pitchers; I think you can call them both power pitchers, but Dellin has the curveball as well."

Betances is 3-0 with a 1.38 ERA in 23 appearances, and 56 of his 98 outs have come this season via the strikeout, including 40 of his last 66.

"I feel good. Since Spring Training, I've felt good," Betances said. "I put in a lot of work this offseason, cleaned some stuff up in my delivery and I'm working every day on the same routines, just trying to get better. That's my goal, and I'm still learning, but the more and more I get out there, the more comfortable I feel."

And the less comfortable opponents seem to be. Batters have posted just a .135 (15-for-111) average against the flame-throwing 26-year-old, who like Rivera was converted from a starter into a reliever.

"There's a different mentality out of the bullpen," Betances said. "You're only going to face the guys once. As a starter, you face them two or three times. But it's definitely a little different. My mentality out of the bullpen is different. I'm just trying to be aggressive, whereas a starter you kind of have to work your way."

Bombers bits

• Triple-A Scranton/Wilkes-Barre second baseman Jose Pirela was named the International League's Batter of the Week for May 26-June 1, leading the circuit with 13 hits while batting .406. He ranks sixth in the league with a .316 average this season.

• Double-A Trenton second baseman Robert Refsnyder was selected as the Eastern League Player of the Week for May 26-June 1, having batted .500 (14-for-28) with a home run and seven RBIs for the Thunder. Refsnyder led all Eastern League players in extra-base hits (nine), doubles (four) and OPS (1.498) last week, tying for first in batting average and triples (two).

• Class A Charleston right-hander Jaron Long, son of Yankees hitting coach Kevin Long, received the South Atlantic League Pitcher of the Week Award for May 26-June 1. Long went 1-0 with a 0.00 ERA in two games, allowing four hits and a walk with 14 strikeouts over 11 1/3 innings.

• Yankees right-hander Shawn Kelley is scheduled to throw a simulated game on Wednesday at Yankee Stadium. If that goes well, Kelley would likely be cleared for a Minor League rehabilitation assignment. Kelley is on the 15-day disabled list with a stiff lower back.

• On this date in 1941, Lou Gehrig died at his home in the Riverdale section of the Bronx from complications of amyotrophic lateral sclerosis. The Iron Horse was 37. Mayor Fiorello LaGuardia ordered flags around the city to be flown at half-staff, and Major League ballparks around the nation followed suit.

Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry. This story was not subject to the approval of Major League Baseball or its clubs.