(SportsNetwork.com) - The Houston Astros have been a pleasant surprise this season and the AL West leaders aim for a three-game sweep of the Seattle Mariners Wednesday at Safeco Field.

The Astros won their fourth straight game and fifth in six tries with Tuesday's 6-3 victory in the Emerald City and starter Collin McHugh sparkled to the tune of three runs over seven innings to run his record to 3-0.

"It was good tonight, we'll take the win," McHugh said.

Pat Neshek pitched a scoreless eighth and Chad Qualls struck out two batters in the ninth inning for his first save.

Jose Altuve highlighted Houston's big eighth inning with a three-run double and Jake Marisnick ended 2-for-2 with an RBI and two runs scored. George Springer and Chris Carter each had an RBI in the win.

The Astros are 7-0 when scoring four or more runs and their 8-6 start matches the 2007 opening to the season.

Houston, which is slated to visit Oakland and San Diego on this nine-game junket, will hand the ball to Roberto Hernandez Wednesday night. Hernandez is 0-1 with a 3.38 earned run average in two starts and did not figure into the decision of a 6-3 loss to the LA Angels last Friday, charged with three runs in six innings.

Hernandez, who gave up five runs in 4 2/3 innings at Texas in his season debut on April 11, is only 2-4 with a 3.42 ERA in nine career games, eight of which have been starts, against the Mariners.

Seattle has dropped two in a row and six of its last eight games, and was leading by a 3-1 score until Houston's big eighth inning. Charlie Furbush took the loss for permitting three runs -- two earned -- in the eighth and Danny Farquhar also gave up two earned runs.

Taijuan Walker started for the Mariners and pitched well, giving up just a run and four hits in 5 1/3 innings. He fanned eight batters and walked four, and left after throwing 101 pitches.

"I thought he was outstanding," Mariners manager Lloyd McClendon said. "He did exactly what I thought he was going to do."

Robinson Cano drove in a pair of runs and Brad Miller went 2-for-3 with an RBI in a losing effort.

Former Astro J.A. Happ draws the start for Seattle Wednesday and will try to rebound from a 3-1 loss to Texas last Friday, when he suffered a hard-luck loss and allowed two runs in seven innings.

Happ, who threw 6 1/3 innings of two-run ball on April 11 at Oakland, is 2-0 with a 2.04 ERA in three career starts against Houston.

The Mariners will host Minnesota for three games this weekend and are 2-3 on a nine-game stay at Safeco Field.

Seattle went 10-9 against Houston last season.