CLEVELAND -- Matt Harrison had his customary between-starts bullpen session on Friday, and he may have worked out a mechanical flaw that has caused problems in his last couple of starts.

Pitching coach Mike Maddux told Harrison that his head wasn't staying straight in his delivery and instead was drifting to the side. That was causing him to throw from an awkward angle and "sling" the ball rather than throw it properly. Harrison immediately made the correction and noticed a big difference.

"I started hitting my spots with my fastball and everything else," Harrison said. "That definitely built some confidence in me."

Harrison has allowed 14 earned runs over his last two starts, driving up his ERA, from 1.66 to 5.41.

Harrison's next start is Monday, against the Orioles. He is being moved ahead of Neftali Feliz, who is being pushed back to Tuesday. The flip-flop allows the Rangers to get their rotation back in the order they wanted: Colby Lewis, Derek Holland, Yu Darvish, Harrison and Feliz. But it will be the second straight start that Feliz has pitched with at least six days since the previous one.

The Rangers don't have another day off until May 24, so the rotation should remain set until then unless weather intervenes.

Rangers remain without Beltre's services

CLEVELAND -- Outfielder Josh Hamilton, despite not being 100 percent because of back spasms, was back in the lineup on Friday night in the series opener against the Indians, but third baseman Adrian Beltre was out of the starting lineup for a third straight game because of a sore left hamstring.

The Rangers have no plans to put Beltre on the disabled list and are hoping that he will be ready to go on Saturday.

"It's truly day-to-day," manager Ron Washington said. "He's available to pinch-hit, and hopefully we can get him in there tomorrow."

And Beltre did pinch-hit in the Rangers' 6-3 loss, sending a fly ball to deep right for the final out of the game.

Beltre injured the hamstring running the bases on April 21 and has missed five of the last 11 games. His last start was on Monday, against the Blue Jays, as designated hitter. He went 3-for-5 at the plate, and running the bases on the artificial surface at Toronto's Rogers Centre aggravated his condition.

While in Toronto he underwent a second MRI, which showed no significant tear, and did not start on Tuesday or Wednesday.

"It's not good enough to be in there tonight but it's not bad enough to be on the DL," Beltre said on Friday. "I don't think it's that bad."

The Rangers are 16-4 with Beltre in the lineup and 1-5 in the five games he did not start. He missed five weeks in the second half of last season with a strained hamstring and has become more understanding about taking time off to rest his legs.

"He has been tremendous about it," Washington said. "He knows his worth. He understand he tried to push it [last year]. He's so understanding. ... I don't even know if it's Adrian."

Hamilton missed all three games in Toronto with muscle spasms on the right side of his back. He said the problem was caused by a couple of ribs popping out of place on Sunday night, and the muscles around them went into spasm in response. He is undergoing daily treatment and maintenance to keep the condition under control.

"It's good enough," Hamilton said. "I took four days off to see if it would get better, and it's a little better. I have been reassured I can't hurt it any further. It doesn't feel totally better, but I can deal with it."

Rangers acquire Spilborghs from Indians

CLEVELAND -- The Rangers on Friday acquired outfielder Ryan Spilborghs from the Indians for cash considerations. Spilborghs, who is not on the 40-man roster, has been assigned to Triple-A Round Rock. He will help make up for the loss of outfielder Leonys Martin, who is sidelined six to eight weeks with a torn ligament in his left thumb.

The Rangers had interest in Spilborghs in the past.

"He's a player we pursued last September when we were looking for an outfielder with experience," said Matt Vinnola, director of baseball operations. "He has tremendous makeup."

Spilborghs, 32, has spent the season with Triple-A Columbus, batting .250 with one homer, 13 RBIs and 12 runs in 21 games. He was hitting.360 against left-handed pitchers. He is a career .272 hitter at the Major League level, with a .345 on-base percentage and .423 slugging percentage in 619 games, all with the Rockies.

Nathan says Rivera can pitch again

CLEVELAND -- Closer Joe Nathan, who missed the entire 2010 season after undergoing Tommy John elbow reconstruction surgery, said that Yankees closer Mariano Rivera could pitch again, even if he misses a full season with a torn ACL in his knee.

"This is going to be more about desire than physical," Nathan said. "The physical thing is nothing if you've done your work and all the things you're supposed to do over the course of your career. If you do that, you can get through the physical thing. He's in great shape because he has taken care of himself. It's a matter of where he is mentally and his desire. ... Does he have the desire to go through the rehab part and play again?"

Rivera, baseball's all-time saves leader, with 608, injured the knee while shagging during batting practice on Thursday in Kansas City. He is expected to undergo season-ending surgery but said on Friday that he wants to pitch in 2013.

"It stinks," Nathan said. "Obviously, this was not the way he wanted to go out. Do I know what he's going to do? Obviously not. I know this year was supposedly his last one. With him, it's like he was Superman. For him to go out like this, especially in batting practice ... It would be one thing if he were on the mound. It goes to show, a lot of weird things can happen."

Worth noting

• Manager Ron Washington on whether he's watching what's happening with the Angels: "Our concern is with us. If we play good baseball, we'll take care of business. It's early. Anything can happen, so we have to stay focused. We can't let our focus stray. If we stay in the position we're in, come September I'll start checking on them. Besides, with the type of team they have, they're not going to stay there. They're too good. That's why we have to take care of our business."

• The Rangers are the first team since the 1938 Giants to not lose two straight until their 25th game after winning the pennant the year before.

• Wednesday's all-right-handed lineup was the first for the Rangers since 2002, when Jerry Narron used one against Oakland pitcher Mark Mulder. That lineup had Michael Young, Herbert Perry, Alex Rodriguez, Ivan Rodriguez, Todd Greene, Kevin Mench, Bill Haselman, Jason Hart and Ruben Rivera.

• General manager Jon Daniels traveled to Round Rock on Friday night to present 2011 American League championship rings to Julio Borbon, Leonys Martin, Michael Kirkman and Mark Hamburger.