Zack Wheeler was “rusty” in his return to the mound for Triple-A Las Vegas yesterday, but improved as his start in Des Moines, Iowa, progressed.

“Honestly, nothing was working real well for me today,” the Mets’ top pitching prospect said after surrendering three runs on five hits, including two home runs, over five innings against the Triple-A Cubs. “Taking 10 days off and missing a start this late in the season and coming back as sharp as you were is tough.”

Wheeler, who struck out two and walked two, missed his start last Friday after tests revealed a slight inflammation of the AC joint in his right shoulder. He received a cortisone shot and resumed throwing last weekend.

Wheeler peaked at 100 mph yesterday, according to a talent evaluator who has been following the righty.

“He pitched like 95-97 most of the time and then it was raining,” the evaluator said. “When it started to rain harder his velocity came down a little bit, but he threw good.

“He gave up two home runs. One was wind blown, the other was hit hard. He looked a little rusty today, but he still threw the ball pretty good.”

Wheeler had three straight dominant starts for Las Vegas before incurring the shoulder soreness. He could join the Mets’ rotation by early next month, but the talent evaluator said he doesn’t believe the club should wait. Wheeler is 3-1 with a 3.91 ERA in nine starts for Las Vegas.

“There’s no reason to wait,” the evaluator said. “He may take a lump here or there, but he’s going to give you quality starts. His stuff is just too good. It’s all better than major league average.”