Clayton Kershaw's back tightened up during Thursday's start, his first for the Los Angeles Dodgers since a stint on the disabled list.
Kershaw won't travel with the team for a weekend series in Colorado, instead remaining in L.A. for tests. Dave Roberts said the tightness was in Kershaw's "mid to lower" back.
"With Clayton's history, there is some concern," Roberts said. "We want to make sure that he is well and good."
Kershaw threw 62 pitches over five innings against the Philadelphia Phillies. He gave up four hits and a run while walking one and striking out five.
"It's beyond frustrating," Kershaw said. "You feel like you're out of the woods and feeling good and then this creeps up on you. I'm frustrated that I can't contribute to the team."