TAMPA, Fla. — Yankees left-hander Andy Pettitte threw 36 pitches during a 10-minute bullpen session today and remains on target to start the third or fourth game of the regular season.

Pettitte originally was to start New York's second game against Toronto on Tuesday but was pushed back due to back spasms.

"It makes me feel good that I got through that and I felt good," Pettitte said. "I could just tell that I felt a whole lot better this morning when I woke up. It loosened up nice for me."

Pettitte is scheduled to pitch in a minor league game Saturday. That outing could be pushed back to Sunday if he feels stiffness Thursday.

"We'll see how I feel tomorrow and make a call," Pettitte said.

Also, Yankees left fielder Johnny Damon was scratched from Wednesday's game against Philadelphia with flulike symptoms. He could miss a couple of days.

Yankees general manager Brian Cashman said left-hander Sean Henn, who has been slowed by left shoulder tendinitis, will start the season on the 15-day disabled list. Henn gave up one hit over a scoreless inning in a minor league game Wednesday.

Closer Mariano Rivera also worked a scoreless inning in a minor league contest, striking out one.

Billy Traber made a strong case to be the left-hander out of the Yankees' bullpen in Wednesday's 4-0 loss to the Phillies. He retired left-handed hitting Chase Utley on a fly ball and struck out Ryan Howard.