ARLINGTON -- Saturday marked the first Major League start for shortstop Oswaldo Navarro, who was recalled from Triple-A on Wednesday when starting shortstop Tommy Manzella went on the disabled list with a fractured left index finger.

"I'm very excited," said Navarro, who hit .298 with four homers and 26 RBIs in 44 games for Round Rock. "I've waited for this opportunity for a long time, and today's the day."

Navarro, 25, played in four games and went 2-for-3 in his previous Major League stint in 2006 with Seattle. He was with the Astros briefly in May but didn't record a start. He entered Saturday with no hits in five at-bats this season at the Major League level.

"I feel better and more prepared mentally and physically, and I'm happy with that," Navarro said. "I want to try to do something to help the team win."

Astros go young with four rookies in lineup

ARLINGTON -- The Astros had four rookies in their starting lineup Saturday against the Rangers, and fielded a fifth player who spent the first two months of the season at Triple-A Round Rock -- starting pitcher Josh Banks.

Houston netted Jason Bourgeois in center field, Chris Johnson at third base, Jason Castro at catcher and Oswaldo Navarro at shortstop. All five players were called up to the Majors within the past week after spending the first part of the season in the Minor Leagues.

Bourgeois, Castro and Johnson entered Saturday a combined 13-for-33 with five RBIs in four games.

Bourgeois started his third game, second in center field, since having his contract purchased Tuesday. Manager Brad Mills said he will give Bourgeois occasional starts against left-handers, resting center fielder Michael Bourn.

"We'll wait and see how everything works out," Mills said. "It's only been a few days since he's been here and things have a tendency to work out as they go. He's looked extremely well on both sides of the ball offensively and defensively since he's been here, so that's nice."

Astros take part in hottest game of year

ARLINGTON -- The Astros and Rangers played a rare summer day game in Arlington, a move that was made so the game could be shown locally on television. Temperature at first pitch was 95 degrees and was expected to rise close to 100 -- Houston's hottest game this season.

Making matters worse, The Astros wore their gray uniform tops, which are heavier than their red tops.

"The heat doesn't bother me one iota," said Astros first baseman Lance Berkman, a Texas native. "We used to play triple-headers in this stuff when I was a kid."

Houston manager Brad Mills said having a younger lineup on the field would be beneficial, but that didn't go into his thinking when filling out the lineup card. Starting pitcher Josh Banks and catcher Jason Castro played in the heat all season at Triple-A Round Rock.

"There's obviously a time where it becomes too hot, and if that's today both teams have to play in it," Mills said. "We'll go through it. Our pitcher has been in Round Rock and pitched in some heat before, and the catcher is a younger guy and has caught in it before."

Moehler awaits next assignment

ARLINGTON -- After picking up his first win of the season by holding the Rangers to two earned runs in five innings Friday, pitcher Brian Moehler will now wait to find out if he's going to stay in the rotation or head back to the bullpen.

"The way he pitched, he sure deserves [another start]," said Astros manager Brad Mills.

Bud Norris will be activated prior to Monday's game and return to the starting rotation in Milwaukee, and he could take Moehler's spot. The rotation is set through Wednesday's game.

"I guess if I did start, the earlier it would be would be Thursday, so I'll kind of wait and see," Moehler said. "I'm sure [pitching coach Brad Arnsberg] will tell me something, probably tomorrow. I'm not going to be able to throw for the next couple of days anyway. If I go in the bullpen it would be Monday or Tuesday."

Moehler is 1-4 with a 5.63 ERA this year in 18 games, including six starts. He's made a career out of switching between the rotation and the bullpen. He has appeared in 330 games in his Major League career -- 250 as a starter.