Even though Roy Oswalt was in a different uniform, the Colorado Rockies had the same meager result against the right-hander on Friday night.

Oswalt continued his dominance against the Rockies, pitching effectively into the seventh inning in his first start of the season and the Texas Rangers won their seventh straight, beating the slumping Rockies 4-1.

"He resembled the same Roy Oswalt I've seen the past couple of years," Colorado manager Jim Tracy said.

Oswalt (1-0) improved to 9-2 lifetime against Colorado with a 1.89 ERA, his best mark against any of the 16 teams he's faced more than three times.

The 34-year-old, who signed a deal with the Rangers on May 29, allowed one run and nine hits in 6-2-3 innings to win for the first time since Sept. 27 when he was with Philadelphia.

This is Texas' longest winning streak since taking eight in a row April 12-21.

"These guys have been rolling," said Oswalt, who threw 81 of his 110 pitches for strikes. "I was just trying to keep it going."

The Rockies fell to 1-12 in interleague play. Their only victory outside of the National League came last Friday against Detroit.

Wilin Rosario had three hits for the Rockies, who have lost 13 of 15 overall.

Colorado's Christian Friedrich (4-4) allowed four runs and seven hits in six innings. The rookie allowed home runs to Adrian Beltre and Mike Napoli.

"They hit a couple of home runs," Tracy said. "That's what really beat us."

Oswalt, who struck out six and walked one, was sharp from the start. His fastball was clocked in the low 90s and he showed off his slow curveball that confused Colorado hitters most of the night.

The Rockies didn't muster much against Oswalt until breaking through in the seventh.

Dexter Fowler tripled with two outs and Texas pitching coach Mike Maddux made a trip to the mound to check on Oswalt. Marco Scutaro lined a double to right to force the right-hander out of the game.

Oswalt, who made four starts in the minors this season after signing, left to a standing ovation. Robbie Ross relieved Oswalt and retired Carlos Gonzalez on a grounder to end the seventh.

Joe Nathan pitched a perfect ninth to earn his 16th save in 17 chances. This is the Rangers' longest winning streak since taking eight straight April 12-21.

The Rockies left 10 men on base in the game and hit into double plays in the seventh and eighth.

"He threw a few more off-speed pitches than I remember," Rockies designated hitter Jason Giambi said. "To me, he was as good he's always been."

Beltre hit a two-run homer in the first that just cleared the fence in right. It was his 13th of the season.

Nelson Cruz had an RBI double before Napoli lined his 12th home run of the season to right to make it 4-0 in the fourth.

Texas catcher Yorvit Torrealba was thrown out by left fielder Gonzalez at home plate in the second trying to score Craig Gentry's single. It was one of four outs the Rangers made on the bases.

Notes: To make from for Oswalt on the roster, 1B Mitch Moreland (left hamstring strain) was placed on the 15-day DL. . Rockies IF Jonathan Herrera was activated from the 15-day DL Friday and made his third career start at SS. . Rangers LHP Derek Holland (left shoulder fatigue) threw 42 pitches in a bullpen session. He will throw again in the bullpen Sunday or Monday. . Beltre hit a liner off Friedrich's back in the fourth, but the left-hander remained in the game.