Stephen Strasburg tries to state his case to be the National League's All-Star Game starter tonight when the Washington Nationals open a three-game series with the Colorado Rockies at Nationals Park.

Strasburg, though, has lost his last two starts and is coming off one of the shortest outings of his career his last time out on Saturday in Atlanta. Strasburg was forced to leave after the third inning, surrendering three runs and two hits with four walks.

"The problem was that he was totally dehydrated," manager Davey Johnson said.

Strasburg has pitched in triple-digit temperature in two consecutive starts, and it might become three on Friday, with the high in Washington projected to be 102 degrees.

"I haven't talked to the medical staff, but he's going in the night game. That's good," Washington manager Davey Johnson said. "But we'll be drinking a lot of water. I don't think we'll be having any transfusions or anything. Unless I need one."

He lost to the Rockies two starts ago in his only other appearance against them.

Strasburg will be trying to help the NL East-leading Nats extend their season- best home winning streak to six games tonight. Washington won its fifth in a row in D.C. on Thursday in thrilling fashion, as a throwing gaffe on a potential inning-ending double-play grounder off the bat of Adam LaRoche plated Bryce Harper with the winning run, helping the Nationals get past San Francisco, 6-5.

"That's what you live for, you live for games like that," Harper said. "It's a lot of fun. We're a team that's not going to stop, not going to quit."

The late-inning heroics made a winner of Tyler Clippard (2-2), who turned in a scoreless top of the ninth.

Harper finished with two RBI, while Ian Desmond and Danny Espinosa slugged back-to-back homers in the seventh inning for the Nationals, who have won seven of their last nine overall.

Colorado, meanwhile, has lost five of six after a 6-2 setback to the St. Louis Cardinals on Thursday. The Rockies haven't won a series since June 1-3, against the Los Angeles Dodgers.

Christian Friedrich (4-6) surrendered six runs on five hits and three walks in the loss for Colorado, which has just three wins in its last 10 games.

Tonight, the Rockies turn to lefty Drew Pomeranz, who is 0-3 with a 3.72 ERA in six starts this season. Pomeranz lost to San Diego on Sunday, but pitched well, giving up just an unearned run and two hits with three walks in six innings.

"[Pomeranz] actually put on a clinic, as far as I'm concerned, on pitching inside and pitching effectively inside," Rockies manager Jim Tracy said. "I don't know how many bats he broke, but if I were to guess, it would be a half- dozen. He looked different than he did earlier."

Colorado split a four-game set with the Nats earlier in the year.