ATLANTA — Boston Red Sox right-hander Clay Buchholz will test an ailing knee during a bullpen session Wednesday in Boston, then find out when he’ll make his next start.

Buchholz set a career high with eight walks and allowed six runs in only three-plus innings Monday before Boston rallied to beat Atlanta 8-6, ending a 10-game losing streak.

Manager John Farrell said Tuesday that Buchholz remained in the game after his left knee buckled.

“So we’ve got to make sure that he gets through his bullpen (Wednesday),” Farrell said, adding he wants to be certain “that knee, where he felt like it was a little hyperextended, doesn’t persist or show any further soreness.”

Farrell said Buchholz initially denied his knee buckled when catcher A.J. Pierzynski went to the mound.

“He didn’t want that to be any part of the reason of why he pitched the way he did,” Farrell said. “But we’ve got to be conscious of it and see how he comes through the bullpen.”

Buchholz is 2-4 with a 7.02 ERA in 10 starts. It’s a dramatic decline from 2013, when he was 12-1 with a 1.74 ERA.

Farrell confirmed that Buchholz’s self-confidence is a concern.

“We can’t deny that,” Farrell said. “We’re not blind to what everyone sees. And yes, there is concern because you’re talking about a guy that was on his way to potentially a Cy Young year last year and now he’s only shown flashes of it, either inside a game or for a start.”

Buchholz said he’s having trouble sticking with progress made on his mechanics in the bullpen before games.

“It’s not fun, I know that. … It seems to be snowballing on me right now.”