By Larry Fine

NEW YORK (Reuters) - New York Yankees general manager Brian Cashman admitted the path to a 28th World Series championship got a little harder with Friday's retirement of pitcher Andy Pettitte.

After failing to sign free agent pitcher Cliff Lee, who turned down New York's offer of about $140 million to sign with the Philadelphia Phillies in December, the absence of Pettitte has left the Yankees rotation in disarray.

"It's obviously one that's incomplete," Cashman told a crowd of reporters after the 38-year-old Pettitte's farewell news conference at Yankee Stadium.

"There is a comfort level with CC Sabathia, Phil Hughes and A.J. Burnett," he said about the returning trio. "We have some kids in the system, as well as non-roster invites that are going to compete and take a run at the remaining spots."

After missing out on the pitching prize of the free agent pool in Lee, the Yankees have signed veterans Freddy Garcia and Bartolo Colon to compete at spring training with journeyman Sergio Mitre and young Ivan Nova.

"When Cliff made his determination, I said patience was Plan B," Cashman said. "You can't force it. I'm willing to take it day by day and step by step, but at the same time recognize that our starting rotation is not where it needs to be.

"Sometimes there's an easy quick fix, and sometimes it's a more difficult, longer road to take. This will be the more difficult, longer road."

Yankees manager Joe Girardi, a team mate of Pettitte's in the 1990s, said the left-hander would be sorely missed.

"I've been through a lot with Andy over his career. Catching him in '96 (when the Yankees ended an 18-year World Series drought), catching him for four years. Coached him, managed him. We're gonna really miss him."

Pettitte, who was 11-3 last year, has a 240-138 career mark including three seasons with the Houston Astros. He stands third on the Yanks' all-time list wins list with 203, trailing only Hall of Famers Whitey Ford (236) and Red Ruffing (231).

Girardi said New York's biggest off-season signing could help compensate for the weakened rotation.

"We're excited about our bullpen and the addition of (Rafael) Soriano with Mariano," he said about adding last year's Tampa Bay closer to his own finisher, Mariano Rivera.

"The bullpen here has been the strength of a lot of the championships and I think it has a chance to be again this year."

(Reporting by Larry Fine, Editing by Frank Pingue)