HOUSTON — A 2-1 loss to the Houston Astros on Wednesday night at Minute Maid Park was the least of the Dodgers' worries as they headed to Denver.

Pitcher Derek Lowe left Wednesday's game because of a strained left groin muscle, an injury that will keep him out of action indefinitely.

Lowe initially injured the muscle while warming for a relief appearance this past Sunday at Dodger Stadium. He felt good enough to make his start against the Astros, but not good enough to get through the fifth inning.

He will have an MRI today.

"It's hard to describe because warming up (Wednesday) I felt it with every single warmup pitch, and it continued throughout the game," Lowe said dejectedly.

What might have pushed Lowe over the edge was a fifth inning at-bat in which he hit the ball on one hop to right fielder Luke Scott, who threw out Lowe out at first base.

"It was a straw," Lowe said of the play at first. "It was an embarrassing straw. But as fast as I was going, I knew I was going slow. I know I'm not fast, but I was trying like heck to kick it into ... I don't even want to say second gear ... one-and-a-half gear."

For the time that Lowe was in the game, he pitched well. He retired 11 of the first 12 batters he faced with his only mistake coming on a 2-0 pitch to Eric Munson in the third inning. Munson hit a line drive that barely cleared the wall in right field to give the Astros a 1-0 lead.

Lowe worked his way out of a tough spot in the fourth inning but threw just four pitches in the fifth before coming out. It was the first time in his career Lowe has left a game because of an injury.

"Running doesn't hurt, nothing activity-wise hurts," Lowe said. "When you land is the only time I really ever feel it. You can ask me tomorrow how I feel, and I'll say fine."

With Lowe out, Brad Penny and Brett Tomko are the only pitchers in the starting rotation who were there when the season started. Tomko is in the rotation filling in for Randy Wolf, who started the season in the rotation but is out because of shoulder soreness. Wolf is on a rehab assignment and could return to the rotation next week. Jason Schmidt is out for the season after undergoing shoulder surgery.

The Dodgers will have to rely on their makeshift rotation, which includes Hendrickson and sometimes Eric Stults. Both pitchers have worked out of the bullpen and in the rotation.

That also means that the Dodgers will have to lean on their bullpen, which was severely overworked as they came out of the All-Star Break.

A complete-game victory by Chad Billingsley on Monday gave the relief staff some rest, but the loss of Lowe forced the Dodgers to use D.J. Houlton, Joe Beimel and Roberto Hernandez on Wednesday.

The Astros' Carlos Lee homered off Houlton in the seventh inning to snap a 1-1 tie.

"Chad did a tremendous job in his game and it kind of got us back in line, and this puts us back behind the eight-ball again, as far as using so many guys," Lowe said.

Former Astro Jeff Kent tied the game at 1-1 with a solo shot in the seventh inning. His team-leading 15th homer of the year marks the season-high eighth straight game in which the Dodgers have had at least one home run, breaking the streak of seven in a row from May 25-June 1.

With the home run, Kent has reached safely in 36 straight games, the longest streak in the majors this season.