SEATTLE -- Pittsburgh Pirates starter Jeff Locke continued his winning ways Tuesday night, even when he had what manager Clint Hurdle called "the lightest stuff he had this season."
The red-hot Pirates didn't need much better from their starting pitcher, as they unloaded a surplus of extra-base hits to beat the Seattle Mariners 9-4.
Pittsburgh (47-30) hit five home runs -- two by leadoff hitter Starling Marte -- and nine of the Pirates' 13 hits went for extra bases. Marte had multiple home runs for the first time in his career, hitting one in the second inning and another in the eighth to go with the triple he had to lead off the game.
"It was a good night for our offense," Hurdle said after his team extended its winning streak to five games.
Pittsburgh had six extra-base hits in the first two innings, including three home runs in the second, while jumping out to a 6-0 lead. That was enough for Locke, who gave up just two runs on four hits in seven innings to win his seventh consecutive decision.
Locke (6-1) allowed two runs over seven innings and had a sizeable lead for most of the night. Tuesday marked the 13th consecutive start in which he's allowed three runs or fewer, and he hasn't suffered a loss since dropping his season debut on April 10 at Dodger Stadium.
"I just want to go out and keep us in the game every time out," Locke said. "We had a pretty good offensive padding."
Hurdle said of Locke, "It was a good night for him to probably have his lightest stuff. We'll look for better stuff next time."
Extra-base hits were a factor in each of Pittsburgh's first nine runs. Marte, Russell Martin and Brandon Inge all homered off Seattle starter Joe Saunders (5-8) in the five-run second inning, then Marte added a solo shot off Carter Capps in the eighth. Gaby Sanchez finished off the scoring for Pittsburgh with a ninth-inning home run, his second in three games.
Seattle's Kyle Seager led off the sixth with a solo home run off Locke, the first homer Pittsburgh's 25-year-old starter had given up since May 11, but by that time it was only enough to cut the Pittsburgh lead to 7-2.
The Pirates added solo homers in the eighth and ninth innings to take a 9-2 lead, giving them 19 runs in their last two games and 35 during the five-game winning streak.
"We had some power jump out there tonight," Hurdle said. "It's been a nice sequence of games. ... They're showing what they're capable of."
The Mariners' Justin Smoak hit a two-out, two-run homer in the bottom of the ninth inning to account for Seattle's final two runs.
Saunders was tagged for six runs on six hits in 1 2/3 innings. Blake Beavan replaced him and allowed just one run over 4 1/3 innings. Struggling Seattle reliever Tom Wilhelmsen had his most encouraging performance in three weeks when he struck out the side in the seventh, his only inning.
"With the way he threw the ball that inning, we just wanted to get him out on a solid note, feeling really good about what he's doing," Mariners manager Eric Wedge said.
Pittsburgh's Pedro Alvarez doubled off Capps in the ninth to extend his current hitting streak to nine games.
With three hits Tuesday, Marte now has 26 multiple-hit games this season. Teammate Andrew McCutchen, who went 2-for-5 Tuesday, has 24 multiple-hit games.
NOTES: The Pirates, who were idle Monday, are now 8-0 when coming off an off day. ... The Mariners placed OF Franklin Gutierrez on the 15-day disabled list and recalled OF Dustin Ackley from Triple-A Tacoma. Ackley, the No. 2 overall pick in the 2009 draft and the Opening Day starter at second base, was hitting .205 with the Mariners before being sent to Tacoma on May 26. The emergence of 2B Nick Franklin at the big-league level precipitated the move of Ackley to the outfield during his 25-game stint at Triple-A. ... Mariners OF Jason Bay was in the starting lineup for the first time since June 16. He had been nursing a hamstring injury. ... Marte continued his remarkable string of extra-base hits. He has four triples, two doubles and two home runs in his last 11 hits. ... Tuesday marked the fourth time in Saunders' eight-year career that he didn't make it out of the second inning. His shortest outing came on Sept. 30, 2006, when he was pulled after retiring just two batters and allowing five runs against the Oakland A's. Saunders' team at the team, the Los Angeles Angels, rallied to win the game 7-6.