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09/14/12 8:04 PM ET

Oswalt plays catch, could throw BP next week

ARLINGTON -- Rangers pitcher Roy Oswalt, who is sidelined with tightness in his right forearm, played catch on Friday and will try again on Saturday. If that goes well, he could have a bullpen session early next week when the Rangers are in Anaheim.

Oswalt is unavailable to pitch out of the bullpen. His last outing was a two-inning start on Sunday against the Rays that was cut short because of discomfort in his forearm. He tried to throw on Thursday but still felt more discomfort.

"It wasn't terrible, but ..." Oswalt said.

Oswalt is 4-3 with a 6.29 ERA in nine starts and four relief appearances since signing with the Rangers at the end of May. Opponents are hitting .328 off him.

"We just have to keep going until he gets better," manager Ron Washington said. "You're always concerned when something is nagging. You hope by now it's gone away, but it hasn't. It's unfamiliar territory. He's never had an arm injury. It could be he's a little tentative, we'll just have to wait and see."

Nathan unavailable on Friday; Ogando will close

ARLINGTON -- Rangers closer Joe Nathan is unavailable out of the bullpen for Friday's game against the Mariners, manager Ron Washington said. Alexi Ogando, who has three saves this season, will close the game if the situation arises.

Nathan pitched three days in a row and blew his second save of the season in a 5-4 loss to the Indians on Thursday. Washington said Nathan might get Saturday off as well, if needed.

"If we have to bang him, we will," Washington said. "If he says he's fine and there's a save situation, we'll give him the ball."

The Rangers are also without setup reliever Mike Adams, who is sidelined with a strained muscle in the back of his right shoulder. Adams said he threw on Thursday and still felt some tightness. He did not throw on Friday, but may try again on Saturday.

Left-handed setup reliever Robbie Ross, who has been on the disabled list with tightness in his left forearm, threw a bullpen session on Friday without any problems. He should be activated at some point during the series with the Mariners.

The Rangers are also starting to like what they're seeing from Koji Uehara, who pitched back-to-back scoreless innings against the Indians on Wednesday and Thursday. He has been scored upon just once in eight outings since being activated off the disabled list on Aug. 25. He missed 2 1/2 months with a strained lat muscle in his right ribcage. But his 2.25 ERA is the second lowest on the staff, and his .190 opponents' batting average is the third lowest.

"He has been darting it down in the zone," Washington said. "His [split-finger fastball] has been tremendous, and he's using his slider a little bit. We've been using him a little more than we wanted, but he needs to see hitters. He's doing a great job. We still have to watch him and protect him, but he has been very convenient with his pitches."

Hamilton back after getting injection in knee

ARLINGTON -- Rangers outfielder Josh Hamilton was back in the lineup on Friday, one day after receiving an injection in his left knee. It's the first time he has been injected in the knee since Spring Training.

Hamilton said the injection was just to put some lubrication in the knee. Hamilton was unavailable on Thursday while waiting for the injection to take effect.

"I've felt it for the last month," Hamilton said. "We play with a lot of stuff we don't let you know about. It's just soreness, that's all it is. A little lubrication and I'm ready to go. It feels a lot better today. It feels 90 percent better."

Hamilton went into Friday's game hitting .258 with seven home runs in his last 16 games. He has 14 RBIs and a .621 slugging percentage during that span, but also 22 strikeouts.

"I feel good at times," Hamilton said. "The biggest thing is not to try and do too much ... not get outside of myself. When I get outside myself, I start chasing pitches out of the strike zone. When I stop doing that, things start clicking.

"I have Adrian [Beltre] hitting behind me, and then Nelson Cruz and [David Murphy] down the line," Hamilton said. "My job here on out is get on base and score as many runs as I can. If there are guys out there, get them in or move them over. Get them in any way we can. We've got guys behind me who can do that, too."

Latest from the Minor Leagues

• The Rangers have extended their working relationship with Double-A Frisco for four more years through the 2018 season. The Rangers have been aligned with Frisco since the 2003 season. Frisco plays at the Dr. Pepper Ballpark just 45 minutes away from the Ballpark in Arlington.

• The Rangers announced they are not renewing the contracts of roving hitting instructors Randy Ready and Luis Ortiz. Earlier this week, the Rangers announced that Triple-A hitting coach Brant Brown and Class A hitting coach Julio Garcia were also being let go.

• Infielders Jurickson Profar and Mike Olt, who played at Frisco before being called up to the Rangers, have been named to Baseball America's first team Minor League All-Star Team. It's the second straight year both have made the team.

Worth noting

• Adrian Beltre, who has some inflammation in his left shoulder, was at designated hitter for the second straight game on Friday. Manager Ron Washington said Beltre will probably start at third base on Saturday.

• Washington also said he would like to get Jurickson Profar in the lineup on Saturday against left-hander Jason Vargas. Profar is a switch-hitter, and this will be his first chance to hit right-handed since being called up at the beginning of the month.

• The Dempster Family Foundation 22q Mystery Bus was at the Ballpark in Arlington on Friday night. The 22q Mystery Bus has been traveling the country to raise awareness of the little known disorder, called 22q11.2 deletion (or 22q, as it is sometimes called). Rangers pitcher Ryan Dempster's Family Foundation is bringing the bus to Texas to help shine the light on this disorder. It is open to the public before and after the game.

T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.