He took batting practice before Thursday's game and tried to run on Friday, without success.
"As soon as I tried to run harder, I couldn't run," Lieberthal said. "It's odd. It's one thing to get hit in the knee. With injuries like that, you at least have a timetable [on how long you'll be out]. With this, I don't know. I know I can't play. It's not like I'm close."
Lieberthal missed his fourth straight game on Friday and won't play this weekend, which is why another stint on the 15-day DL is a strong possibility. The team can make the move retroactive to June 6.
The catcher missed most of May after being hit in the left knee by a John Thomson pitch on May 5. He was activated on May 29, and had gone 2-for-20 (.100) since returning.
If Lieberthal heads to the DL, right-handed pitcher Brian Sanches might be recalled from Triple-A Scranton/Wilkes-Barre, leaving the catching duties to Sal Fasano and Chris Coste.
Fasano has started the past four games, and was in the starting lineup Friday. Manager Charlie Manuel said he's concerned about the 34-year-old's durability.
"I hope he doesn't wear down," Manuel said.
Rookie Eude Brito's two-start audition didn't fare well, and the lefty was optioned to Triple-A on Friday and replaced by outfielder Chris Roberson.
Brito went 0-2 with a 10.38 ERA in two starts and didn't reach the fifth inning in either start. He admitted to Manuel that he was trying too hard to impress the organization.
The Phillies opted for Roberson over a pitcher because Manuel likes his speed and defense off the bench, especially if Shane Victorino is used earlier in the game as a pinch-hitter.
Sanches might be back soon enough if Lieberthal heads to the DL.
Because of an off-day, the Phillies won't need a four-man rotation until June 17, and it's a possibility that Jon Lieber might be ready to return then.
"I'm not putting a timetable [on returning]," Lieber said. "All I've heard from other people is that if you rush back, you're going to make it worse."
Lieber is eligible to come off the disabled list on June 14. Other options to start include the recently signed Adam Bernero -- who's pitching for Scranton -- reliever Ryan Franklin and Double-A pitchers Scott Mathieson and Gio Gonzalez.
Franklin seems to be an option only in a long-term situation, and Manuel hasn't had that need yet.
"Somewhere along the line, when we need starting pitching, [Franklin will] definitely be considered," Manuel said. "But we haven't sat down and talked about that yet. In the regular season, you get in a pickle where you have to do things and right now, with pitching, that's kind of where we're at, kind of scuffling to find ways to make it better."
Franklin, who signed this winter to be a starter and did nothing in Spring Training to change that thinking, is still in favor of a switch, but understands the reluctance to make him a spot starter.
"I'm still trying to get adjusted to the role I'm in, and it's not easy," Franklin said. "I've approached them and told them that I would definitely be available. But they told me they didn't want to put me in there for one game and then not have me [out of the bullpen] four days."
Coste may catch on:
The possibility has increased that Coste, a 33-year-old rookie, might log a start behind the plate. He caught five innings on May 27, when he entered as part of a double switch.
"I just hope they have the confidence to let me [start]," said Coste. "Fortunately, they let me catch a good amount in Spring Training to prove that, but I've never started a Major League game with a lot on the line. Every day, I'm excited to get that shot to catch. It's my best position, but it's also my favorite."
Manuel said often in Spring Training that Coste has the skills to be a backup catcher in the big leagues, and he would love that opportunity.
"I'm 33 and it took me a long time to get here," Coste said. "It's a good story and all, but eventually, you have to do something to stay here. I had [Cleveland manager] Eric Wedge as a manager [in the Minors] for three years. He said it takes a special person to get to the big leagues, but it takes a more special person to stay in the big leagues. That's the biggest reason why I'm excited to get the chance to catch a game or two, because I'm going to have to do something to try and stay here."
Cory Lidle, who opposes Washington's Livan Hernandez on Saturday at 1:20 p.m. ET, is in one of his typical stretches. He's pitched six innings in each of his previous five starts and allowed three or fewer earned runs in four of them. He has faced the Nationals twice this season, and is still looking for his first win against them.