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Bud Norris tries to cap off a sensational month of May this evening when the Houston Astros close a four-game set with the Colorado Rockies at Coors Field.

Norris has been terrific this month, going 4-0 with a major league-best 1.17 earned run average. He's only allowed four earned runs in his last six starts and three of them came his last time out on Saturday in Los Angeles, as the Dodgers reached him for three runs and eight hits in 4 2/3 innings.

The 27-year-old righty, who became the first Astros starter to not last five innings since April 13, escaped with a no-decision in that one and is 5-1 on the year with a 3.34 ERA. He hasn't lost since surrendering seven runs in Milwaukee back on April 24.

Norris has faced the Rockies twice, but has pitched to a 4.50 ERA against them without recording a decision.

Colorado will counter with righty Jeremy Guthrie, who is 2-3 with a 5.31 ERA. Guthrie allowed six runs for the second straight start on Saturday in a loss against Cincinnati, although only two were earned.

He beat the Astros back on April 6, yielding three runs and four hits in seven innings.

Colorado beat the Astros for the third straight time on Wednesday, as Carlos Gonzalez smacked three of the Rockies' three home runs in a 13-5 win.

"He's in a different place right now," Rockies manager Jim Tracy said. "He's in a place where you never thought you'd see him be. He's stepping to just another level."

Michael Cuddyer hit his second grand slam of the season in the first inning. Dexter Fowler added a three-run homer for the Rockies, who have won five of their last seven.

Despite allowing five runs on 11 hits in six innings, Christian Friedrich (3-1) picked up the win for Colorado.

"His only mulligan was in the third inning when he started getting behind in the count," Tracy said. "When you get yourself in that position, [hitters] become a lot more [selective]. I really like the way he rebounded."

Lucas Harrell (4-4) struggled for the Astros, surrendering nine runs in five- plus innings, and giving up 10 hits and three walks.

"We allowed five home runs with the first one being a grand slam," Astros manager Brad Mills said. "We battled back, we got some hits, but they got five homers."

Houston has now lost six in a row at Coors Field, its longest skid in Denver since dropping all seven at Mile High Stadium to the expansion Rockies in 1993.