Haniger went through a hard workout on Thursday to test the oblique and felt some soreness afterward that caused the club to raise a caution flag rather than push him too fast with an injury that can linger.
"He probably got a little too aggressive yesterday, so we're going to give him a day off today and just kind of slow him down a little bit," manager Scott Servais said prior to Friday's game with the White Sox.
"At the end of the workout yesterday, he was still a little tender. Nothing totally alarming, but we figured let's slow down a little instead of just shooting him out and now he's in a competitive situation."
The original hope was to let Haniger play several games over the weekend near his home in California so he could potentially rejoin the Mariners for the start of their eight-game road trip Tuesday against the Nationals in Washington.
But the plan will be on hold now until Haniger's oblique shows it's fully ready for game action.
"You don't want to go out and try to play in a competitive situation, even if it's on a rehab in the Minor Leagues [unless you're 100 percent]," Servais said. "When you're in the box, you want to hit the ball and you're not going to slow down and take it easy. So we have to be careful with him."
• Left-hander James Paxton (strained forearm) came out of Thursday's 25-pitch bullpen session with no issues and will throw off the mound again Sunday before heading out for a Minor League rehab start next week. Servais said Paxton could be ready to rejoin the club at the start of its next homestand at the end of the month.
• Second baseman Robinson Cano (sore right quad) did some light running, then threw and took batting practice on Friday, and appears on track to come off the 10-day DL as scheduled next Tuesday.
• Pitchers Felix Hernandez, Hisashi Iwakuma and Drew Smyly all played flat-ground catch on Friday without any apparent problems as they work back from injuries. Hernandez and Iwakuma are dealing with shoulder issues that figure to sideline them into June, while Smyly is on the 60-day DL with a strained elbow that could keep him out until midseason.
• The Mariners still haven't announced a Sunday starter in the spot opened by optioning Chase De Jong back to Tacoma. Servais said a two-inning relief stint Thursday didn't eliminate long reliever Casey Lawrence from consideration. Dillon Overton, who has made one spot start this season, is also a possibility, or the Mariners could recall a pitcher from Triple-A Tacoma.
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB. This story was not subject to the approval of Major League Baseball or its clubs.