PITTSBURGH -- Jason Grilli will take the next step in his rehabilitation this weekend.
The Pittsburgh Pirates closer will play catch, marking the first he has thrown since going on the disabled list July 23 with a strained right forearm.
The Pirates say it is too early to tell exactly when Grilli might be able to be activated. However, manager Clint Hurdle said Sept. 1 could be a logical date since that is the day the major-league roster limit expands to 40 from 25.
It would likely not take much time for Grilli to build enough arm strength to pitch in games. The Pirates have not used the 36-year-old for more than one inning in any of his 45 appearances this season.
Grilli has converted 30 of his 31 save opportunities this season and has a 2.34 ERA.
"He's still ahead of schedule, Hurdle said. "We're pleased with his progress."
The Pirates might also be able to add right-hander James McDonald to their deep bullpen in September. He has been on the disabled list since May 1 with right shoulder discomfort.
Though McDonald has worked almost exclusively as a starter for the Pirates since being acquired during the 2010 season from the Los Angeles Dodgers in a trade, he is set to begin a throwing program at the Pirates' training facility in Bradenton, Fla., that will build him up to 50 pitches. That would enable McDonald to pitch in middle or long relief.
McDonald pitched 5 1/3 innings of scoreless relief for the Dodgers in two appearances in the 2008 National League Championship Series against Philadelphia.
--Wandy Rodriguez is taking small steps toward returning to the Pirates' rotation, but the team doesn't yet whether he will pitch again for them this season.
Rodriguez is scheduled to throw off a mound for the second time on Saturday before the Pirates play the Colorado Rockies at Denver. However, the Pirates do not have a timetable for when Rodriguez might be able to go on a rehab assignment.
Finding rehab starts for Rodriguez might be problematic as the minor-league regular season ends on Labor Day. The Pirates may have to look for alternatives, such as pitching live batting practice or simulated games with the major-league club.
"Wandy won't be a Sept. 1 add," said Hurdle. "The progression he has to go through, to build up to at least five innings and 80 pitches, will take us past that date."
Rodriguez has been on the disabled list since June 6, and the Pirates ideally would like to have him as another starting option for the final weeks of the regular season and possibly the postseason.
"Whether I get it or not, I don't know," Hurdle said. "Like I'm always telling my daughter, 'Get what you can get, and don't throw a fit.'"
Rodriguez entered the season as the Pirates' No. 2 starter behind right-hander A.J. Burnett, but has been limited to 12 starts. Rodriguez is 6-4 with a 3.59 ERA.
"If we get Wandy back, it'll be nice, but we know we're capable right now with what we have," said Hurdle, whose team entered Frday leading the major leagues with a 3.07 ERA.