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8/26/2014 12:07 A.M. ET

With tight right side feeling better, Asdrubal pinch-hits

PHILADELPHIA -- Nationals second baseman Asdrubal Cabrera had a full workout prior to the Nats-Phillies series opener on Monday as he looked to get past the tightness in the right side of his rib cage that forced him to leave Sunday's contest against the Giants before the eighth inning. He sustained the injury after hitting a grounder to short in the bottom of the seventh.

"He did some early hits and he came out of that fine," Nationals manager Matt Williams said. "And so we're going to put him through the full workout today -- take grounders and run and make sure. We want to give him a day to make sure that he's OK for tomorrow potentially."

Cabrera proved he was OK when he got a chance to pinch-hit in the ninth inning of Monday night's 3-2 loss. He singled on a grounder to right field to put any lingering doubts about the injury to rest.

"I wanted to stay away from him if at all possible tonight to give him a day to make sure," Williams said. "But we knew after batting practice. He went through a full BP and swung from both sides and had no issues. So he should be good to go."

Souza progressing on rehab assignment

PHILADELPHIA -- Nats outfielder Steven Souza Jr. is three games into his rehab assignment as he recovers from a right shoulder strain that he suffered on Aug. 8 after crashing into the outfield wall while attempting to rob Freddie Freeman of a homer. He has been on the disabled list since Aug. 10, and an MRI showed no structural damage.

After beginning his rehab assignment with one game at Class A Hagerstown on Thursday, Souza was moved up to Class A Advanced Potomac for two games over the weekend.

"He played three. He's doing the normal progression," Nationals manager Matt Williams said. "He's getting his ABs. Any time you're off, though, you have to make sure you get that timing back. So that's where he's at. The time frame, we don't know yet. We want him to do well and want him to make sure that his timing's good and his swing feels good. And when that time is, we'll call him back."

Through his first 12 at-bats in the big leagues, the 25-year-old has just one hit.

Erik Bacharach is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.