Twins closer Glen Perkins had more back problems Wednesday, and it might force him to miss the start of the Twins' upcoming road trip.

Perkins felt some stiffness in his back Tuesday afternoon, and felt worse when he tried to play catch before the game.

"He came in and felt a little sore," Twins manager Paul Molitor said. "He went out and played catch and it really started to spasm on him again."

Perkins was sent for a Magnetic Resonance Imaging exam to make sure nothing serious was wrong.

"There's no bulging disk," Molitor said. "There's no serious issue that we have to look at, other than we gotta figure out how to keep this from continuing to flare up. There's a good chance he might stay back and spend some time with our guys to see if we can get him back and see if we can get him out on the trip at some point."

The Twins will leave on a three-city road trip Thursday that begins with stops at AL West-leading Houston and AL Central-leading Kansas City.

Perkins has missed time over the past two-plus weeks because of a sore neck that required a cortisone shot, then a sore back that flared up last week. Kevin Jepsen has saved five games while Perkins has been out. Any loss of Perkins — 2-4 with a 2.68 ERA and 32 saves — for an extended period of time will make the Twins' battle for a wild-card spot even tougher.

It hurts, but he hits

Miguel Sano has a sore right hamstring. He can't play in the field. He can't run the bases at full speed. The injury should keep him on the bench.

When asked how his hamstring was Wednesday, Sano grinned and said "Bad."

The Twins even sent him for a precautionary MRI to make sure there wasn't a serious problem. There wasn't, and Sano was in the starting lineup against the White Sox.

Sano has been such a force in the middle of the lineup that he was named AL rookie of the month for August. He continued his tear Wednesday, crushing a 434-foot home run to center off the batter's eye in the second inning.

The Twins can't afford to have a player providing so much punch to not be in the lineup. So Sano was in the cleanup spot once again. And the wild-card-dreaming Twins need him in the lineup. He just has to take it easy on the bases.

"I'm going to run like I did [Tuesday]," Sano said.

Sano injured his hamstring during the last road trip and was held out of Friday's game against Houston. He's played ever since, and the Twins got a look of how limited he was Tuesday when he eased his way from second to third on a single by Eddie Rosario in the second inning. Twins manager Paul Molitor spoke with Sano to get an understanding of what he's capable of doing with his legs.

Molitor knows what Sano is capable of with his bat. Sano won rookie of the month honors after batting .278 with seven doubles, nine home runs and 26 RBI in 27 games. He led all AL rookies in runs scored (18), home runs, RBI and walks (16).

"If it's going to be that, I'm still going to take the at-bats," Molitor said. "If that is all we're going to get on the bases, we'll take it to let him get his swings in. I'm hoping it improves. When you're out there playing every day, it is tough to get better. And that's the hard part. Hopefully he gets back to where he can be a little more functional."

Yes, we have no Berrios

Twins General Manager Terry Ryan ended the mystery Wednesday. Starting pitching prospect Jose Berrios will not be called up for a September look. Instead, he will make one more start for Class AAA Rochester, then head home to Puerto Rico.

Ryan said Berrios' workload this season was a factor in his decision. Berrios, 21, has thrown 161⅓ innings this season after pitching 139⅔ last season.

Etc.

• Righthander Phil Hughes, on the 15-day disabled list since Aug. 10 because of a sore back, will throw in the bullpen Thursday as he begins to build up arm strength to return to the rotation.