CLEARWATER, Fla. - With Cliff Lee on the 60-day disabled list, the Phillies' offseason signing of Aaron Harang becomes even more important.

Harang, a 36-year-old righthander, is in line to become the team's No. 2 starter behind ace Cole Hamels now that Lee is resting the torn common flexor tendon in his left elbow.

That, of course, is dependent on Harang's staying healthy, too.

But despite already missing two of three scheduled spring starts because of back discomfort, Harang said Monday he is confident he will begin the regular season on schedule. The veteran is scheduled to start Thursday night's Grapefruit League game against the New York Yankees in Tampa. He probably will pitch three innings.

Speaking minutes after completing a bullpen session Monday morning, Harang didn't seem at all worried about the missed time.

"It's frustrating, but it's not as frustrating as if this was later in camp," he said. "I don't view this as any type of setback. I can progress through and catch up in my innings pretty easily."

The Phillies signed the 6-foot-7, 260-pound Harang in January to a one-year, $5 million deal. The typically durable journeyman has logged more than 200 innings in four of his 13 major-league seasons, including last year with the Atlanta Braves when he had a 3.57 ERA.

His lone Grapefruit League outing so far spanned two innings against the Baltimore Orioles on March 9. He allowed three hits and walked two but did not give up a run. He was scratched from what would have been his first and third spring outings.

Harang said the minor back issue that cost him last Saturday's start was different than the one that scratched him from his original spring debut. The latest was "more just a straight [muscle] spasm" he felt closer to the middle of his back when he woke up one morning. He said it's gone now.

"It's being cautious," he said of Saturday's missed start. "There's no reason to push this, because you don't want this to linger."

Harang isn't setting a number on how many innings he would like to pitch before the team heads north. More important is building up his arm to account for the breaks between innings, which can also be simulated in bullpen and live batting practice sessions at the Phillies' spring training complex. Even if he builds up to only 85 or 90 pitches in a start by the end of spring training, he will still be on track, he said.

"It's more of just the up and down," he said. "It's not even the pitch count in the game as much as the break in between [innings]."

@jakemkaplan