Bryce Harper left Thursday’s game with what appears to be a left knee injury. (AP Photo/Gregory Bull)

Bryce Harper limped out of Thursday night’s game against the Rays after planting awkwardly on his left knee while making a throw in the sixth inning. Manager Matt Williams said the team diagnosed him with a mild left hamstring strain, a diagnosis Harper said he considered a relief.

In the sixth inning, with the Nationals leading, 3-2, and runners on first and second, Rays shortstop Asdrubal Cabrera singled to right field. Harper charged and tried to fire home, but slipped on the wet turf. He said his right knee gave out, which required him to put all his weight on his left knee, which bent deep under the weight.

As the throw sailed away between third and home, allowing two runs the score and the Rays to take a lead, Harper lay on his back in the outfield, clutching the back of his knee to his chest. Williams and trainer Lee Kuntz hustled out, and Kuntz examined the knee before they helped Harper up. He hobbled off the field himself, but slowly.

“Got my hamstring — lower hamstring into the knee a little bit,” Harper said. “But it didn’t feel very good. Was in pretty good pain. Was a little scared at the same time because I could feel a little more on the lower half of it. But see how I am tomorrow and go from there. ”

Harper had surgery to repair the bursa sac in that left knee after the 2013 season, and was hit there with a pitch last weekend in Milwaukee. He said he has no history with hamstring injuries.

“With the way it felt, I’ve had problems with my left knee before, had surgery on it, so you know it was definitely really scary. It didn’t feel all that great when I was laying there,” Harper said. “So pretty scary, but being able to talk to the doc a little bit, see what he thought, see how it felt. I’m very happy with what it feels like.”

Harper said, and Williams agreed, that the 22-year-old will see how he feels Friday. Harper has not had an X-Ray or MRI exam on the knee, and said the injury “is not at that point yet,” though if it still feels “pretty terrible” over the next few days, he may go that route.

Harper did not rule out playing Friday, though that seems unlikely. He emphasized the need to be smart with the injury. The Nationals hope it does not require more than a few days’ rest: Harper leads the team with a .344 average to go with his 22 home runs, 53 runs batted in and 53 walks.