PHILADELPHIA -- Bryce Harper could be back by next Monday.

The 29-year-old is scheduled to begin a rehab assignment Tuesday night with Triple-A Lehigh Valley. He plans to play with the IronPigs through Saturday. Harper will not play Sunday, which will allow him to fly with the Phillies from Philadelphia to Phoenix on Sunday night if he feels he is healthy and ready to play.

Philadelphia opens a three-game series against the D-backs next Monday.

“It is in play,” Phillies interim manager Rob Thomson said.

But it depends how Harper’s left thumb feels and if he feels he is ready to face big league pitching. He has not faced pitching since June 25 in San Diego, when Blake Snell hit him with a fastball and broke his left thumb.

If Harper returns Monday, he could play in the Phillies’ final 34 games. If he returns Sept. 2 in San Francisco, which would be the first game of the next series on the road trip, he could play in the final 31 games.

“It’s always a goal to have in mind, where you want to be and what you want to do,” Harper said Sunday about his return, which was previously pegged for some time during the road trip. “But we don’t know until I play [rehab games]. We can all talk about when and where, but we just don’t know until I play and how I feel with contact and things like that.

“I’m going to be smart with it. I’m going to be very smart with it and come back when I see fit and when my hand is feeling better and I can help this team every day and not just play two days, one day off, play two days, one day off. I’m going to come back at full strength playing.”

Harper said Sunday that his thumb feels about 80-85 percent like normal.

“I think our biggest thing is the [mobility] of it, I guess, isn’t there,” he said. “That’s why I say 85, somewhere in there, just because of the [mobility] part of it. But I think the strength and everything like that is there. I think as we progress, it’s going to get better and better, I hope.”

Harper was having one of the best seasons of his career when he broke his thumb, despite playing since mid-April with a torn UCL in his right arm that limited him to DH duties. He was batting .318 with 15 home runs, 48 RBIs and a .984 OPS in 64 games. At the time of the injury, Harper ranked fifth in the National League in batting average, sixth in on-base percentage (.385) and second in slugging percentage (.599).