SEATTLE -- After initially believing that veteran right-hander Felix Hernandez was merely dealing with fatigue in his arm after cutting short a Minor League rehab outing last weekend, the Mariners are now having the former American League Cy Young Award winner tested for further issues in the right lat muscle that has been bothering him for the past five weeks.

Manager Scott Servais said the 32-year-old was getting an MRI exam on Tuesday after being evaluated on Monday by the Mariners' doctors. He threw 31 pitches in 2 1/3 innings in his first rehab outing for Triple-A Tacoma on Friday in San Antonio, but he had hoped to build up to 50-60 pitches in that start.

“Felix had some discomfort in the back of his shoulder,” Servais said. “It’s concerning enough to get new images of that. Let’s find out exactly what is going on in there.

“He didn’t feel any specific pitch or anything. I talked to him yesterday and he said when he started to warm up in the third, it didn’t feel right. It wasn’t a sharp pain or anything, he just felt fatigue, felt weak and shut it down at that point.”

Hernandez allowed two runs on two hits with two walks and a strikeout before he called for the trainer and was taken out of the game.

Hernandez was initially diagnosed with a Grade 1 strain of the lat muscle after a start on May 11 in Boston, when he gave up seven runs on six hits and three walks in 2 1/3 innings.

That outing dropped him to 1-4 with a 6.52 ERA in eight starts on the season. This is the final year of a contract that is paying him $27 million.

Haniger on the mend

Mitch Haniger was back in the Mariners clubhouse on Tuesday and said he was feeling better, but the 28-year-old right fielder won’t be allowed to begin running or ramping up his activities for about another week as he recovers from a ruptured testicle.

Haniger doesn’t have a specific timeline for his return, but the Mariners won’t rush the 2018 All-Star back from his June 6 injury, when he fouled a ball off himself in the third inning of a game against the Astros at T-Mobile Park.

Haniger stayed in for three more innings and another at-bat before taking himself out. He wound up in the hospital the next day for surgery.

“I knew something wasn’t right, but I’m never going to come out of the game unless I feel like it’s too much to bear or I can make it worse,” Haniger said. “At that point, I just kind of told myself, if I have to dive, am I going to be able to do that? I just didn’t want to make anything worse, especially with the location of the injury.”

Servais said the Mariners will force Haniger to take his return slowly.

“Mitch wants to get out there and play. He’s going to do everything he can to heal up as fast as he can.,” Servais said. “That’s just how he’s wired. Patience is not a big thing for him. That’s how you want guys to be, but on this one we have to be really cautious and smart.”

But Haniger insists that things could have been worse and he’ll start wearing protection in the future.

“Fortunately, it’s not going to be a crazy long recovery,” he said. “There are other injuries you can sustain on a baseball field that take six months to a year. I’m happy it was nothing like that. I’ve had some of these freak injuries happen, but at the end of the day, you just focus on the next step to get back on the field with my teammates and get back out there.”

Worth noting

Reliever Sam Tuivailala threw a 30-pitch bullpen session on Tuesday and said he feels ready to resume a Minor League rehab stint soon, though he doesn’t know yet when that will happen. The right-hander was working his way back from Achilles tendon surgery and throwing for Tacoma until his arm started feeling fatigued about three weeks ago.