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8/30/2014 6:12 P.M. ET

Mikolas pushes innings barrier

HOUSTON -- Rangers pitcher Miles Mikolas has thrown 102 innings this season between Triple-A Round Rock and the big leagues. That's the most he has thrown in his six-year professional career.

That's one of the reasons the Rangers scratched him from Saturday's start against the Astros when he felt some fatigue in his shoulder during his last bullpen session.

"I haven't started in awhile, so it's better to be safe than sorry," Mikolas said. "So we're going to tap the brakes a little bit. I'm a little more tired than normal. Nobody likes their arm not feeling 100 percent. This is the first time starting in five years and my body is adjusting. Let it catch up, settle down and be ready to go in my next start."

The Rangers haven't decided when that will be. Nick Martinez starts on Sunday against the Astros and then Colby Lewis, Derek Holland and Nick Tepesch are scheduled to pitch against the Royals during the three-game series that starts on Monday in Kansas City.

The earliest Mikolas would pitch is Thursday against the Mariners in Arlington. But the Rangers could also use Scott Baker, who has won two straight starts. He allowed two runs in 6 1/3 innings on Friday night against the Astros.

"We'll see," manager Ron Washington said. "Baker isn't going to be available for three days so we'll wait and see after that."

Carp designated for assignment; Holland off DL

HOUSTON -- The Rangers were forced to designate first baseman Mike Carp for assignment to make room for pitcher Derek Holland on Saturday.

The Rangers, by rule, were forced to take Holland off the 60-day disabled list after his medical rehab assignment expired on Thursday and add to him to the active roster. The Rangers also needed to add him to the 40-man roster.

Carp was the move because the Rangers are committed to looking at Ryan Rua at first base for the remainder of the season. Carp was claimed off trade waivers from the Red Sox at the beginning of August, but was just 5-for-40 in a part-time role at first base.

"He didn't really get it going but that didn't come into play," manager Ron Washington said. "With all the young kids we want to see, there just wasn't a whole lot of at-bats for him. We needed to make a roster move. It's unfortunate because he is a pro."

With Carp gone, the Rangers are without two of their left-handed bats as Jim Adduci is on the seven-day concussion disabled list and not eligible to come off until Friday.

Tepesch joins September callups

HOUSTON -- In a paperwork move, Nick Tepesch has joined the short list of players who will be called up in September when the rosters are expanded to up to 40 players.

Tepesch was optioned to Triple-A Round Rock to make room for Robbie Ross Jr., who was recalled on Saturday to start against the Astros. The move has no impact on Tepesch's schedule, it was just a convenient way to make room for Ross.

Since Round Rock's season ends on Monday, Tepesch can be recalled on Tuesday. The Rangers aren't expected to call up many players.

Ross and infielder Ryan Rua were expected to be called up but are already here. That leaves pitchers Lisalverto Bonilla and Spencer Patton as the likely additions to the bullpen and infielder Luis Sardinas as the only position player.

The Rangers aren't expected to add an extra catcher as is customary in September. Tomas Telis and Robinson Chirinos will continue to share the duties with J.P. Arencibia available in an emergency.

Outfielder Jake Smolinski might be able to join the Rangers before the season is over. He is on the disabled list with a small fracture in his left foot and has just resumed baseball activities.

Holland takes more fielding practice

HOUSTON -- Derek Holland was on the field early Saturday afternoon going through more defensive drills with manager Ron Washington. The Rangers have been testing Holland regularly through the summer to see how his left knee responds.

But Holland was the one who requested this workout.

"Just because I'm back doesn't mean I'm going to stop working on stuff," Holland said. "I want to make sure the sharpness is there and I can field my position. It feels good, no issues at all."

Holland is scheduled to make his first start for the Rangers on Tuesday against the Royals. He has been sidelined all season after undergoing surgery on his left knee in January and has made six starts on rehab assignment with no issues. The Rangers are still concerned how the knee will hold up, especially when Holland has to field his position.

"I think it will get better," Washington said. "He is moving well enough to do what he has to do. It will get better but his knee is finally where he doesn't have to think about it."

Worth noting

• Ryan Rua batted fifth in his Major League debut on Friday. He is the first Rangers player to make his Major League debut in one of the top five spots in the order since Jason Romano batted leadoff in his first game on April 17, 2002. Rua is the first Rangers player to debut in the fifth spot since Ruben Sierra on June 1, 1986.

• Rua is also the 11th player to start at first base for the Rangers this season.

• The Rangers won their semifinal series against the Giants in the Dominican Summer League. They have advanced to the finals for the second straight year.

• Eight of the Rangers' 13 runs on Friday were driven home by rookies. Michael Choice and Rougned Odor each had three while Daniel Robertson and Tomas Telis both had one. The last time the Rangers had at least eight RBIs from rookies in one game was their 30-3 victory over the Orioles on Aug. 22, 2007. They had 13 in that game from Jarrod Saltalamacchia (seven), Travis Metcalf (four) and David Murphy (two).

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.