Pirates 4, Mariners 2: Jordy Mercer singled home the go-ahead run with two outs in the top of the ninth inning to lift streaking Pittsburgh to its sixth consecutive victory and a two-game sweep of host Seattle.

Pedro Alvarez started the winning rally with a leadoff single and moved to second on a sacrifice bunt before Yoervis Medina intentionally walked Travis Snider. That brought up Mercer, who foiled the strategy with a single up the middle before a wild pitch by Medina plated an insurance run.

Neil Walker belted a two-run homer and Vin Mazzaro (4-2) pitched two scoreless innings before Mark Melancon worked out of a jam for his second save. The Pirates completed a 7-2 road trip to move 18 games over .500 for the first time since 1992. Charlie Furbursh (1-4) took the loss, giving up one run in two-thirds of an inning.

Seattle, which fell to 3-7 in its last 10, answered Walker's fourth-inning blast with Michael Saunders' sacrifice fly in the bottom of the frame and Raul Ibanez's solo blast - his 18th - in the sixth.

Mariners ace Felix Hernandez struck out 11 - one shy of his season high - while allowing two runs on six hits in seven innings. Pirates starter Jeanmar Gomez, who came off the 15-day disabled list earlier Wednesday, gave up an unearned run on three hits in five frames.

GAME NOTEBOOK: Alvarez went 2-for-4 to extend his hitting streak to 10 games, one shy of his career high in 2010. ... Ibanez hit his ninth homer in June, tying Baltimore's Chris Davis for the most in the American League during the month. He is one shy of his homer total for 2012 with the New York Yankees. ... The Pirates have a day off before returning home to face National League Central rival Milwaukee for three games while the Mariners host the Chicago Cubs in a three-game set beginning Friday.