CC Sabathia, left, and Andy Pettitte chat before a game...

CC Sabathia, left, and Andy Pettitte chat before a game against the Tampa Bay Rays. (Aug. 25, 2013) Credit: AP

Andy Pettitte did more than simply watch CC Sabathia's bullpen session on Monday.

The guest instructor actively instructed, primarily helping to teach Sabathia a cut fastball, something the Yankees' ace hopes to add to his repertoire this season.

"He was showing me a grip with the cutter,'' Sabathia said after throwing a four-inning simulated game indoors at Steinbrenner Field because of heavy rain Thursday morning. "I used it today and it worked pretty good, so I'm anxious to take it into a game.''

Sabathia, who in the past has referred to his slider as a cutter, believes it can be an effective pitch, much in the way it was for Pettitte toward the end of his career.

"This is going to try to be a true cutter,'' Sabathia said.

The lefthanders are close friends, and Pettitte has counseled Sabathia on surviving as a pitcher with diminishing velocity. That adjustment period did not begin well for Sabathia last season, when he went a career-worst 14-13 with a 4.78 ERA. Sabathia's fastball averaged 91.1 mph in 2013, down from 94.2 when he joined the Yankees in 2009.

As he struggled a year ago, Sabathia said pitching coach Larry Rothschild, former bullpen coach Mike Harkey, former advance scout/head video coordinator Charlie Wonsowicz and Pettitte all discussed the possibility of having him add a cutter.

Sabathia said the conversations stemmed from "just trying to figure things out last year.''

But Pettitte, who was in camp earlier this week as a guest instructor, stayed in Sabathia's ear about it, as did Rothschild.

"Any time Andy can talk to somebody, it helps to reinforce the things that we've talked about,'' Rothschild said after the Yankees' 4-3 victory over the Phillies at Bright House Field.

The 33-year-old Sabathia said adding something new, or at least attempting to, never hurts.

"Especially in this game, you always have to keep involved and try to get better,'' Sabathia said. "I'm still trying to master the pitches that I throw. My changeup is coming along better this spring, I feel good about it. My two-seamer is always a work in progress. So I'm always trying to get better.''

Rothschild said "absolutely'' the pitch can become an effective part of Sabathia's arsenal. "Lefthanders have a lot of success with that pitch,'' Rothschild said.

Earlier in the week, Pettitte said he has no doubt that Sabathia will make the necessary adjustments and not only become effective again, but a top-of-the-rotation-caliber starter.

"CC's got everything it takes to be successful,'' Pettitte said Monday. "I know he's doing things to try and accomplish that. He's too much of a competitor not to be successful. And he's got a great club around him, so he's going to be just fine.''

Pettitte, who learned to pitch with diminished velocity as he got older, is just the pitcher Sabathia wishes to model himself after.

"Even with the velocity drop and everything, he was still effective because he knew how to pitch,'' Sabathia said. "It's something I've picked up from him the last couple of years. It's something I definitely went through last year, so I'll be able to handle it.''

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