Giancarlo Stanton took batting practice on Friday at Yankee Stadium, and Aaron Boone said there’s still no timeline for when he might be able to return from the sprained knee that has kept him out since June.

But the manager believes Stanton still can be a productive player if he’s able to return next month.

“I think it’s realistic,’’ Boone said before the Yankees’ 8-2 loss to the A’s in The Bronx. “I don’t want to put any expectation on it at this point. The bottom line is he’s dealt with a couple of significant injuries this year that have interrupted his season at the beginning and when he came back.”

So far, Stanton has played just nine games this season, sidelined with a torn left biceps, a cortisone shot in his left shoulder and the right knee injury he suffered on June 25.

Stanton is expected to take BP, do some light running and defensive drills during the homestand and depending on how he feels, could go down to Tampa to see live pitching at the end of next week.

The Yankees had won 13 straight against left-handers before Brett Anderson beat them on Friday. They also were held without a homer for the first time in 11 games and without an extra-base hit for just the fourth time this season. They have lost all four of those games.

Aaron Judge extended his hitting streak to a season-high eight games.

Yankee Stadium gates will open at 11 a.m. on Sunday for the Mike Mussina Hall of Fame Celebration, set to begin at 12:30 p.m.