ST. PETERSBURG -- Instead of joining his teammates Monday for the start of a three-game series against the Tampa Bay Rays, Astros slugger Yordan Alvarez was sent back to Houston in order to undergo tests on his sore neck.

Manager Dusty Baker said prior to the series opener at Tropicana Field that Alvarez has been dealing with neck discomfort “for about a week.” Baker added that he “hopes” Alvarez will not require a stint on the injured list.

“Hopefully, it’s not too bad, so we’ll see,” Baker said.

Baker was unsure if Alvarez will be able to rejoin the team in St. Petersburg or be ready to play when the Astros return home to face the Phillies on Friday. It will depend on what shows up on the exams in Houston.

“It’s been something that’s been going on for a week,” Baker said.

The diagnosis comes on the heels of a big weekend at the plate for Alvarez as the Astros swept the Braves in Atlanta. He bashed go-ahead home runs on both Friday and Saturday and followed that up with a game-tying, two-out, two-run single in the eighth inning Sunday. Alvarez entered Monday with a .253/.367/.533 slash line, and he ranked second in the Majors with 27 RBIs.

Outfielder Kyle Tucker was slotted in the No. 3 hole in Houston’s lineup Monday, a spot usually reserved for Alvarez. Hot-hitting rookie Corey Julks got the start in left field, batting sixth, while Yainer Diaz was the designated hitter.