FORT MYERS, Fla. -- The road back to the Tigers' bullpen for Joel Zumaya resumed Monday, when the hard-throwing reliever threw a light side session off the mound.

It marked the first time Zumaya threw successfully off a mound since March 2, when he had an impressive outing in Detroit's exhibition against Florida Southern. Zumaya had a sore right shoulder the next day, costing him more than a week and resulting in a visit to Dr. James Andrews. He then lost more time to a cramp that developed in his trapezial muscle between his neck and right shoulder.

Monday's throwing session lasted about five minutes, according to Tigers head athletic trainer Kevin Rand. Assuming he feels fine on Tuesday, Zumaya's next step will be a more extensive side session, throwing harder and for a longer stretch.

With two weeks left before the Tigers open their 2009 season in Toronto, it might be enough of a track to get Zumaya back in a game by the time Spring Training ends, but getting him onto the active roster might take a while longer.

Manager Jim Leyland has yet to completely rule him out, but reiterated his previous doubts that Zumaya can be ready in time for Opening Day.

"It's starting to become a real short Spring Training," Leyland said.

And at some point, Leyland would prefer to know that he can use Zumaya on successive days without concern for his shoulder. Stretching him out to that level would tack more time onto Zumaya's comeback timetable.

"In the big leagues, unless you use guys for long relief, you can't use guys who can't pitch back-to-back [days]," Leyland said.

If the Tigers don't have Zumaya for Opening Day, they'll have to figure out how to use the back end of their bullpen without him. Leyland hasn't yet named a closer between Brandon Lyon and Fernando Rodney. The two relievers combined to give up a seven runs over their two innings Monday against the Red Sox. If one somehow isn't the standard closer and the other the regular setup man, they could conceivably alternate. Detroit would also need an additional reliever to pick up some eighth-inning work.

If Zumaya avoids additional setbacks, the time lost should not be long. What the Tigers are trying to avoid is a more severe setback that takes his absence deeper into the season and forces Detroit to go with longer-term plans, to say nothing of more arm concerns for Zumaya.

In other injury news, Clete Thomas just completed his throwing program as part of his rehab from Tommy John ligament replacement surgery last summer. He threw to bases on Monday.

The throwing program is the last obstacle before Thomas can start playing in the outfield again, probably later this week. He has been limited to designated-hitter duties so far this spring.