HOUSTON - So much for the nasty 1-2 punch the Rangers starting rotation could deliver to opponents.

Cole Hamels is likely out until the All-Star break.

The sharp pain Hamels felt in his right side Tuesday night while warming up for a scheduled start at Houston was diagnosed Wednesday as a right oblique strain after an MRI exam. Hamels met with Rangers medical director Dr. Keith Meister, who confirmed the diagnosis. The team said Hamels will miss "approximately eight weeks."

"We've dealt with this before," Rangers general manager Jon Daniels said. "We've dealt with a lot worse than this before. We've been in this spot previously. It's not a blind attitude, that I think it's gonna get better, but I know we are going to work to make it better. It's a challenge, but one that we will push through."

It will be the longest stretch of time Hamels has missed due to an injury in his career.

The Rangers recalled right-hander Anthony Bass from Triple-A Round Rock to replace Hamels on the roster. Bass had been sent out on April 28 and was only eligible to return for a player on the DL since he was optioned less than 10 days ago.

Hamels, 33, missed a month in 2007 with an elbow strain and ended up making only 28 starts. It was the last time he failed to make 30 starts or pitch at least 190 innings in a season.

It robs the Rangers of what was expected to be their top asset going into the season: A dynamic 1-2 punch at the top of the rotation with Yu Darvish and Hamels.

It is not terribly dissimilar from 2015 when the Rangers lost Darvish for the season in spring training and lost Derek Holland for the first four months during his first start. They came back to win the AL West.

"There are certain waves [of emotion] that are going to move across the clubhouse," manager Jeff Banister said. "You need those type of players out there performing for you because they are elite performers. However, there are times when those kinds of things can galvanize a club and put them back into the spot where they need to be where they perform best: as a group. These type of things allow a team to draw closer because of the necessity of it all. They have been through this before. It's not new to them."

It also leaves the Rangers' pitching staff scrambling. A.J. Griffin, who will be activated on Thursday, will replace Hamels in the rotation. But the immediate move was to recall Bass to give them a long relief option for Wednesday after Alex Claudio replaced Hamels on a few moments notice Tuesday and threw a career-high 65 pitches. On Thursday, the Rangers will have to make another move in order to create room for Griffin. That very likely could be Bass, but it would also leave the Rangers short-handed in long relief in the short-term.

With Hamels out, the Rangers rotation is now Darvish, Martin Perez, Andrew Cashner, Nick Martinez and Griffin.

The Rangers are awaiting the return of Tyson Ross. Ross' recovery from Thoracic Outlet Syndrome has been slowed by back spasms, but he has thrown off a mound twice in the last four days. It is not likely Ross would be an option for the rotation before the end of May - and that might be an aggressive schedule.