SEATTLE -- A Mariners lineup that has been hitting on all cylinders of late could be without American League RBI leader Nelson Cruz for several games as the big designated hitter is dealing with tightness in his right calf.

Cruz was pulled from Tuesday's 12-3 win over the Twins in the fourth inning and wasn't in the lineup for Wednesday night's game after undergoing an MRI earlier in the day.

Cruz has been dealing with some soreness in the calif since a week earlier in Colorado, but had gone 8-for-13 with two home runs over his past five games.

"He's tried to play through it, but last night it was barking a little," manager Scott Servais said prior to Wednesday's game. "He had the MRI taken today. I don't know how long he'll be out, maybe a day or two. He's got something going on there with the tightness in the calf."

The Mariners have been hit hard by injuries all year. Even with the recent return of James Paxton , they're still missing three starting pitchers -- Felix Hernandez , Hisashi Iwakuma and Drew Smyly -- while shortstop Jean Segura is also on the 10-day disabled list with a high ankle sprain and right fielder Mitch Haniger has missed six weeks with an oblique strain.

Seattle has scored 69 runs while winning seven of its last eight games and Cruz has been major force in the cleanup spot. He's posted a .299/.383/.563 line with 14 homers and 46 RBIs in 57 games on the year and is the leading vote-getter for the starting DH spot on the American League team for the All-Star Game presented by MasterCard.

"He's been swinging the bat really well and is a big part of our lineup," Servais said. "We're trying to play for the big picture and would hate to lose him for a significant time. So a day here or there is probably the right thing to do."

Backup catcher Carlos Ruiz replaced Cruz at designated hitter in Wednesday's game.

Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter [ @GregJohnsMLB]().