McLouth was injured while taking batting practice on Friday in San Diego and missed the entire three-game series. The All-Star center fielder is listed as day-to-day, but the exact date of his return is still in question, according to Pirates manager John Russell.
"There's still just a little discomfort in there," Russell said. "We have to get that out and slowly get him back into some baseball activities. The next few days we should have a pretty good indication of when we're getting him back."
Even if McLouth feels 100 percent on Tuesday, it's possible he would still have to wait for his return.
"He's still going to have to go through some tests before we get him back on the field," Russell said.
McLouth is one of three starting position players currently out of the lineup. Catcher Ryan Doumit (right wrist) and Jack Wilson (left-middle finger sprain) are on the 15-day disabled list. In addition, the team's pitching staff has also been hit with the injury bug as Phil Dumatrait (left shoulder) and Craig Hansen (neck spasms) are on the 15-day DL.
With all of the injuries, Pittsburgh has won five of six and seven of its past nine games.
"It shows a lot of character," Russell said. "[Injuries] are part of the game. These guys have been very good about sticking together."
Jeff Zampanti is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.