Pittsburgh ? Jason Bay had an eight-RBI game for the second time in less than a year, and the Pittsburgh Pirates ran their winning streak to seven by beating the Milwaukee Brewers, 13-2, Friday night for a doubleheader sweep.

Tony Alvarez’s grand slam supported another strong start by Oliver Perez in the opener, an 8-1 Pirates victory that ended Milwaukee’s five-game winning streak. The Pirates are on their best spurt since winning eight in a row from Sept. 1 to Sept. 8, 2000.

Bay, acquired with Perez in the Brian Giles trade with San Diego a year ago, had three two-run doubles and a two-run homer, matching the eight RBIs he had Sept. 19 against the Cubs. His doubles came in the third, fifth and eighth innings.

Bay’s big night included a disputed homer — his 10th, the most of any NL rookie — off Jeff Bennett in the seventh. Bay’s drive bounced off a fan’s hands in the first row of the bleacher seats, and left fielder Geoff Jenkins immediately sought an interference call.

The umpires huddled briefly before signaling home run, causing Brewers manager Ned Yost to argue unsuccessfully for several minutes.

Bay had nine RBIs in the doubleheader and is hitting .299 with 34 RBIs despite missing the first month of the season after shoulder surgery.

Pirates starter Josh Fogg (6-6) won for the sixth time in eight decisions since an 0-4 start, taking a 6-0 lead into the seventh before allowing Jenkins’ 11th homer. Salomon Torres gave up pinch-hitter Brooks Kieschnick’s RBI single before getting out of the inning with the help of shortstop Jack Wilson’s leaping catch of Keith Ginter’s bases-loaded liner.