The Texas Rangers are in first place in the American League West, but they enter Monday feeling a little nervous about the condition of Yu Darvish.

While the Rangers visit the Oakland Athletics for the opener of a three-game series, Darvish will be in Dallas getting his shoulder examined.

The right-hander was originally slated to make his fourth start Monday after completing the 14-month rehab process from March 2015 Tommy John surgery. However, on Saturday, the Rangers announced Darvish would be scratched due to shoulder tightness.

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"It's a situation where we are going to get him to see a doctor, get an MRI and make sure he's all right," Texas manager Jeff Banister said. "We want this guy to continue to pitch, so we're going to be conservative and make sure he's OK. Not push the envelope."

Trouble began for Darvish when he exited after five innings Wednesday against the Houston Astros. He was examined after the game, and no structural damage was discovered.

He threw a bullpen session Friday, but a day later, following a four-pitch bullpen session, Darvish shut it down. A few hours later, he was scratched from the scheduled Monday start.

"I have heard it's common for players that have had Tommy John surgery to have issues like this," Darvish said in a statement to reporters in Seattle. "Right now I don't want to push it and make it worse. It's a precaution. We hope it's nothing serious and that I can be back soon."

While the condition of Darvish's shoulder remains a mystery, so does Monday's starting pitcher. Banister said left-handed reliever Cesar Ramos was "most likely" to get the start but did not fully commit to him. Ramos is 1-2 with a 3.58 ERA in seven appearances (three starts) and has made two appearances spanning five innings since May 21.

The murkiness regarding Darvish's shoulder is not the only physical issue Texas is dealing with. Adrian Beltre missed his fourth consecutive game Sunday due to a hamstring injury, and although Banister said the third baseman is making progress, the team does not have a timetable for his return.

In the meantime, the Rangers kept winning, as their 6-4 decision at Seattle on Sunday was their eighth victory in 10 games. Cole Hamels allowed one run in seven innings, and Mitch Moreland and Ian Desmond hit two-run homers.

While the Rangers have won seven of nine meetings with Seattle, they were outscored 19-7 in a three-game sweep in Oakland from May 16-18 but are 15-5 since then. The A's owned a 19-22 record when Khris Davis homered four times in the sweep. Since then, the Athletics have lost 14 of their past 21 games.

Oakland ended a seven-game losing streak Sunday by getting home runs from Marcus Semien, Jake Smolinski and Danny Valencia in a 6-1 victory over the Reds at Cincinnati. During the skid, Oakland batted .219 and posted a 5.16 ERA.

"You have to stay positive," Smolinski said. "It's a long season, a lot of things can happen. We just have to even out those tough spots we've been hitting. We just have to stick with it and come out every day ready to play."

The first pitch of the game will start about an hour after the Golden State Warriors begin Game 5 of the NBA Finals against the Cleveland Cavaliers at Oracle Arena across the parking lot. Oakland will hope Sean Manaea can pitch as well as Stephen Curry can shoot 3-pointers.

Manaea is 2-3 with a 6.20 ERA but has pitched better recently, going 2-3 with a 4.18 ERA in his past five starts. Manaea last pitched Tuesday in Milwaukee, when he allowed five runs and six hits in seven innings during a 5-4 loss to the Brewers.

The right-hander's only start against Texas was also his first career victory. On May 16, he allowed one run and four hits in 6 2/3 innings of a 3-1 win.