PHILADELPHIA -- Bryce Harper’s back has improved since he felt “mid-back spasms” in the first inning of the Phillies' 6-2 win over the Nationals on Thursday night at Citizens Bank Park, but not enough to play Friday against the Twins.

Harper remains day to day.

“We’ll see how I feel tomorrow,” Harper said.

Harper said he did not tweak his back with a particular play or movement Thursday, saying only that his back started to bother him in the first inning. He said he didn’t leave the game at that point because he thought he could loosen up the back.

“I wasn’t able to get it loose to where I wanted it to be,” Harper said.

Harper has had back issues in the past, but he said this is unrelated. Harper is batting .293 with seven home runs, 38 RBIs and an .809 OPS in 83 games this season. He is batting .316 with a .962 OPS in 42 plate appearances this month.