"There's obviously concern, but I think we play it out this week to see where we're at," Girardi said. "He's going to continue to play catch and do some exercises that a pitcher would normally do, and we'll go from there.
"We're going to proceed, and it's either going to be he's healthy or he needs surgery."
Tanaka will head to New York on Friday and undergo strengthening exercises at Yankee Stadium over the weekend with the hopes of pitching again in September. The 25-year-old insists he has felt no pain in his elbow, but rather general soreness throughout his entire arm.
Depending on the severity, a UCL tear often times requires surgery, but Tanaka avoided it when the injury was initially diagnosed and instead went the rehab route. He believes the latest setback could simply be a result of not throwing much over the last month.
"I want to be a little bit cautious," Tanaka said through an interpreter. "I haven't been throwing for a couple of weeks and then I started throwing again and built up the number of pitches. I think that's the reason there's a little extra bit of soreness."
Tanaka, who threw 49 pitches in a simulated game at Comerica Park on Thursday, was slated for another simulated game on Tuesday, but Girardi said that has been canceled. It's possible Tanaka could throw his next bullpen in a week, Girardi said. The Japanese right-hander, who is 12-4 with a 2.51 ERA over 18 starts, will do some light throwing in the meantime.
While Girardi is concerned about how his pitcher is feeling, he said there are no plans for Tanaka to see any doctors or shut him down. That's because Tanaka hasn't pinpointed an exact location of the soreness and stressed that he hasn't felt any pain.
"When we ask him is there one spot, he does not point to one spot, he just says general soreness," Girardi said. "He wants time to physically catch up a little bit here."
Chris Toman is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.