In the last seven games, the Rangers' leadoff hitters are hitting .440 with five runs scored and six walks.
Martin, who gets his 12th start as the leadoff man Saturday night against the Astros, has a slash line of .340/.421/.480 at the top of the lineup. Robertson, who reached based three times as the leadoff man Friday night, will start against left-handed pitchers.
Houston is starting Scott Feldman, a right-hander Saturday night.
"Robertson will play when it's time for him to play," manager Ron Washington said. "If for some reasons, something goes down and I have to play him against a righty, I won't hesitate to do that either. But right now, that's his role."
Holland works on fielding: Derek Holland did some fielding drills and threw a bullpen session prior to Saturday's game.
The Rangers didn't request Holland take fielding drills, it was done on his own.
"I got to work on it," Holland said in regards to his fielding. "Just because I'm (with the big club) doesn't mean I can't stop doing anything. Once the season ends, it's back to square one. Yeah, I feel great, no issues at all."
Mikolas to get more rest: Miles Mikolas was scratched Friday night from his scheduled start Saturday with shoulder issues. Mikolas (2-5, 6.44 ERA) doesn't expect to miss another start, which is supposed to be next weekend. Yet, the Rangers are being cautious with a pitcher who hasn't been a starter on a regular basis in such a long time.
"First time starting in five years," Mikolas said. "My body is kinda adjusting and I need it to catch up."
The club has no plans to give Mikolas an MRI exam and will continue to monitor his progress.
Base Hits: Washington said he likes how rookie catcher Tomas Telis calls a game and says listening to pitching coach Mike Maddux and first base coach/former big league catcher Bengie Molina between innings only helps him get better. ... The Rangers lead the majors with 20 rookies used this season. 1B Ryan Rua started Friday night against Houston. The club also leads the majors with pitchers used at 36 and will surpass the league record when Holland pitches Tuesday.