WASHINGTON (AP) _ Nationals star Bryce Harper strained his left hamstring while taking an awkward tumble making a throw, and Washington lost to the Tampa Bay Rays 5-3 on Thursday night.

Manager Matt Williams said Harper had a mild strain and would be further evaulated Friday. There was no estimate on how long Harper might be out.

The All-Star right fielder slipped and fell on the wet grass while trying to throw home on Asdrubal Cabrera’s single in the sixth inning.

Harper held his left leg while down on the ground for a few minutes and then gingerly walked off the field under his own power, escorted by members of the Nationals’ training staff.

Joey Butler homered for the AL East-leading Rays, who took three of four in the home-and-home interleague set.

Chris Archer (8-4) won his fifth straight decision. Brad Boxberger closed for his 16th save.

Doug Fister (2-3) returned from the disabled list and allowed five runs in 5 1-3 innings.

Yunel Escobar got five hits for the Nationals.