Pirates 11, Padres 5: Clint Barmes hit his first career grand slam and Neil Walker also homered while matching a career-high with five hits as Pittsburgh snapped an 11-game home losing streak to San Diego.

The Pirates sent up 14 batters during a nine-run fourth inning en route to beating the Padres in Pittsburgh for the first time since Sept. 18, 2009.

San Diego built an early 5-0 lead before seeing the lead evaporate to end a six-game winning streak.

Pittsburgh’s Erik Bedard (7-12) scored twice and allowed five runs (three earned) and five hits in five innings.

The Pirates trailed 5-1 entering the bottom of the fourth and the first run crossed when Pirates catcher Michael McKenry walked against Ross Ohlendorf (4-3) with the bases full. Barmes then smacked a high fastball off the left-field foul pole to give the Pirates a one-run lead.

Andrew McCutchen drilled a two-run double, Garrett Jones had an RBI triple off the center-field fence that San Diego’s Cameron Maybin was unable to grab and McKenry capped the uprising with a single to left.

San Diego’s Chris Denorfia led off the game with a booming homer over the left-center field fence and San Diego added three more first-inning runs on a single by Jesus Guzman and a two-run throwing error by Barmes.

The Padres stretched the lead to 5-0 in the second when Chase Headley hit a little nubber that started foul and then rolled into fair territory. McKenry chased the ball down and made a sprawling underhanded toss to retire Headley but Logan Forsythe scored from second base with home uncovered.

Walker homered in the seventh to give Pittsburgh an 11-5 lead.

Ohlendorf was charged with seven runs (six earned) and five hits in three-plus innings.

GAME NOTEBOOK: The nine runs allowed in the fourth were the most San Diego has given up in an inning since the Boston Red Sox scored 10 in an inning against the Padres last season. … The five-hit game was Walker’s second of the season. He also had five against the San Francisco Giants on July 8. … Denorfia’s leadoff homer was his second of the season and San Diego’s fifth overall. … McCutchen was hitless the first two games of the series and finished up 2-for-13. … The Padres signed veteran OF Mark Kotsay to a one-year contract extension for 2013. Kostay is batting .290 as a pinch hitter. … Pirates OF Travis Snider didn’t start after leaving Saturday’s game with a hamstring injury but appeared as a pinch hitter.