St. Louis, MO -- (Sports Network) - Jason Bay's three-run pinch-hit home run in the eighth inning lifted the Pittsburgh Pirates past the St. Louis Cardinals in an 11-5 comeback win at Busch Stadium in the finale of a three-game series.

Freddy Sanchez and Jason Michaels drove in two runs each for the Pirates, who took the first and last games of the series. Doug Mientkiewicz and Chris Gomez each had three hits and three runs scored, while Nate McLouth homered and drew three walks.

John Grabow (3-1) picked up the win with two-thirds of an inning of scoreless relief, and the Pittsburgh bullpen combined to throw five shutout innings behind starter Ian Snell, who allowed five runs on 11 hits in four frames.

Chris Duncan went 2-for-5 with a pair of runs batted in and a pair of runs scored for the Cardinals, losers in seven of their last nine. Troy Glaus finished 3-for-4 and drove in a run, Yadier Molina went 2-for-3 with an RBI and two walks.

Jason Isringhausen's (1-5) struggles continued, as he was tagged for four runs -- three earned -- on two hits and two walks in one-third of an inning in relief of Joel Pineiro, who surrendered four runs on six hits in five innings.

As Pittsburgh trailed 5-4 with Isringhausen on in the eighth, Mientkiewicz worked a leadoff walk. Ronny Paulino followed with a single, and Mientkiewicz came home with the tying run when Isringhausen fielded Gomez's tapper but threw the ball away trying to start a double play. Bay capitalized on the mistake, crushing a fly ball that just cleared the fence in left and dropped into the Pittsburgh bullpen.

Pinch-hitter Raul Chavez added an RBI double off Ron Villone in the top of the ninth, and Sanchez followed with a two-run bloop single to put the game away.

McLouth put the Pirates on top with one out in the first, launching a solo homer to right.

St. Louis countered in the bottom of the frame, as Duncan and Albert Pujols put together back-to-back singles before Rick Ankiel drove in Duncan with a sacrifice fly. A single by Glaus and a walk to Molina loaded the bases, but Snell retired Adam Kennedy to escape the jam.

Ankiel and Glaus picked up back-to-back singles in the home third, and Ankiel came in to score the go-ahead run when Molina grounded to short for a fielder's choice.

The Cardinals continued the assault in the fourth, as Brendan Ryan and Skip Schumaker started the inning with singles, then Duncan followed by lining a double to right to score both runners and give St. Louis a 4-1 edge. Glaus followed up with an RBI single to right, pushing the lead to four runs.

Pittsburgh rallied in the top of the fifth, as three straight singles to start the frame produced a run when Gomez knocked in Mientkiewicz. Two outs later, McLouth walked to load the bases, and Michaels delivered with a two-run single to left that cut the lead to 5-4.

Game Notes

The Cardinals gave up more than 10 runs in a game for the first time all season...Pittsburgh was 6-for-15 with runners in scoring position, while the Cardinals were just 2-for-16...The Pirates finish off their six-game road trip with a three-game set against the Cubs at Wrigley Field...The Cardinals open interleague play at home on Friday with the start of a three-game series against the red-hot Tampa Bay Rays.