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7/1/2014 8:50 P.M. ET

Lee throws simulated game, nearing first rehab start

MIAMI - Cliff Lee continues to recover from his strained left elbow, taking another step forward Tuesday at Marlins Park as he threw 60 pitches in a three-inning simulated game.

"We're on pace," Lee said.

Lee said he feels ready to begin a rehab assignment, which could happen Sunday with Class A Clearwater. That decision could come Wednesday, when the Phillies and Lee see how his elbow responded from Tuesday's effort.

"I've been feeling better every day," Lee said. "A couple rehab assignments then hopefully back up."

If Lee makes two rehab starts he should be in line to rejoin the Phillies' rotation after the All-Star break, although the Phillies did not rule out just one rehab start and a return shortly before the break.

Ruiz recovering slowly from concussion

MIAMI -- Phillies catcher Carlos Ruiz is recovering slowly from a concussion he suffered Thursday when he was hit in the head by a pitch at Citizens Bank Park.

"Carlos' [status] is maybe a little more serious than we originally thought, unfortunately," general manager Ruben Amaro Jr. said. "He's had concussion issues in the past, so we have to be careful with him."

Ruiz, who also spent time on the disabled list in 2010 because of a concussion, did not travel with the team to Florida.

Backup catcher Wil Nieves is recovering from his strained right quadriceps in Clearwater, Fla. He is eligible to be activated Friday, which remains a possibility, although he will need to play rehab games first.

Worth noting

• Triple-A outfielder Darin Ruf has been sidelined recently with a wrist and knee injury, but he began playing games again with the Gulf Coast League Phillies.

"I think he felt it on his wrist on one swing, but he generally he felt good," Amaro said. "He's in good shape."

• Amaro said Triple-A shortstop Freddy Galvis, who has been out with a broken collarbone, is "coming along really well. He's taking grounders, should take some swings soon. We should be able to get him in games the next 10-12 days. Freddy is going to play very soon."

• Double-A Reading left-hander Jesse Biddle is on the inactive list to clear his head after struggling on the mound. He is expected to meet with former Phillies ace Roy Halladay at some point. Halladay overcame struggles early in his professional career before developing into one of the most dominant pitchers of his era.

Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.