ARLINGTON -- Problem No. 1 for the Rangers is now batter No. 1.

On Monday, the Rangers lost Shin-Soo Choo, the club's most reliable leadoff man in a season when the position has been terribly transient, probably for the remainder of the regular season. If not more.

In a 5-2 win over Oakland, Choo was hit in the upper left forearm by erstwhile Ranger Ross Detwiler with an 88 mph sinker that obviously didn't sink. Choo suffered a fracture, and the Rangers said he would be put on the disabled list. They did not list an expected time he'd be out. He will be examined Tuesday by team medical director Dr. Keith Meister to determine if surgery is necessary.

For reference, however, they cited some similarity to the forearm fracture Robinson Chirinos suffered in April. Chirinos ended up with a plate in his forearm and missed 60 days. There are, however, only 48 days left in the regular season.

It will be the fourth trip to the DL this season for Choo, who has already dealt with calf, hamstring and back issues and was playing in just his 45th game Monday. It was game No. 120 of the Rangers' season.

"It's obviously very challenging news," manager Jeff Banister said. "I feel for Choo. He's such a key part of this club and this organization; you feel terrible for him, personally. It's a gut punch and one that we will be challenged with, but we have to continue to play."

The Rangers will recall outfielder Ryan Rua from Triple-A Round Rock to replace Choo on the roster, but Rua won't fill his role in the lineup.

It's not clear who will.

When he's been healthy this season, Choo has made the Rangers' offense go by moving back into the leadoff spot when Delino DeShields failed earlier in the year. He took a .362 leadoff OBP into the game. It ranked third among AL leadoff hitters.

When Choo hasn't been healthy, the Rangers have tried Rougned Odor (31 starts) and Jurickson Profar (26) with mixed results.

The aggressive Odor, who likes to swing big, has a .259 leadoff OBP; Profar has a .328 leadoff OBP but has struggled in the spot (and really everywhere) since the All-Star break. He is 6 for 38 (.157) with a .273 OBP in 44 leadoff plate appearances since the All-Star break. DeShields has had four starts in the leadoff spot since returning from a long stint in the minors and is 3 for 14 with one hit by pitch.

"It's a challenge just not having Choo in the lineup, whether it's the leadoff spot or not," Banister said. "The professional at-bats, the ability to get on base, the power threat from the leadoff spot, it all changes the structure of our lineup somewhat. We'll need to find someone who can solidify the leadoff spot for us."

Perhaps the biggest question is whether Banister will broaden the search past the guys he's used most often as fill-ins for Choo. The Rangers' OBP leader is Elvis Andrus, who led off in 2010 for a World Series team but has just 40 games of experience there since. After a month-long experiment back in the leadoff spot in 2013, he acknowledged feeling a bit of tentativeness there and hasn't had an at-bat at leadoff since.

He is a different hitter, though, than he's been in the last several years. And he demonstrated that again Monday with a two-out fourth-inning single that scored the Rangers' first run of the game. It broke a 24-inning scoreless streak for the club. Andrus' .290 batting average and .752 OPS both would rank as career highs. His .346 OBP is one point off the career best he set in 2011.

The Rangers broke the game open in the fifth after Choo was hit by the pitch, and consecutive singles followed. Adrian Beltre then blasted a grand slam that changed the game.

He got the opportunity because the guy at the top of the order found a way on base.

If the Rangers are to continue to find ways to create big innings, they must again find somebody to reach base consistently from the top of the order.

Twitter: @Evan_P_Grant

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