SAN FRANCISCO — The Giants' modest four-game winning streak came to an end Monday, a surprisingly short night for opening day starter Madison Bumgarner.
Rene Rivera hit a go-ahead three-run homer in the fifth to follow his two-run double for a career-high five RBIs, single handedly backing Tyson Ross in the San Diego Padres' 6-4 victory
Bumgarner didn't make it past the fifth inning against a shorthanded Padres. The left-hander failed to pitch into the sixth just three times in 2013, but already has matched that total through his first six starts.
Coming off a complete game, Bumgarner struggled with his command through five rocky innings. He walked two and loaded the bases in the first but got out of the jam with a strikeout. In the fourth inning, an error and double put two in scoring position for Rivera, who lined a double down the left field line to give San Diego a 2-0 lead.
The Giants struck right back to take the lead. Angel Pagan hit a leadoff single in the bottom of the fourth and scored on Hunter Pence's triple. Three batters later, Michael Morse hit a two-run single up the middle to give Bumgarner a 3-2 lead.
He couldn't hold it. Rivera followed a single and walk with a three-run blast to left-center field. It was the first homer in three years for the 30-year-old backup catcher.
Bumgarner was pulled after five and charged with four earned runs on seven hits and four walks, a season high. He has failed to get past the fifth inning three times this season, matching his total for all of 2013.
The Giants inched closer in the bottom of the fifth when Brandon Hicks, who won Sunday's game with a walk-off homer, hit a towering solo shot to center. The homer was the fourth of the season for Hicks, a career-high.
Buster Posey hit a one-out double off Padres right-hander Tyson Ross in the sixth and went to third on Morse's single to right. After reliever Alex Torres struck out Pablo Sandoval, Brandon Crawford drew a walk to load the bases. Hicks unloaded on a fastball and looked to have a go-ahead grand slam, but the ball died on the warning track in left field.
Ross (3-3) did just enough over 5 1/3 innings to beat the Giants for the second time in 11 days, allowing eight hits and four runs with four strikeouts and two walks.
Giants manager Bruce Bochy stuck with first baseman Brandon Belt in the lineup's No. 3 spot despite a rough weekend. Belt was 0 for 12 against the Cleveland Indians with nine strikeouts, and had whiffed in 11 of his previous 15 at-bats entering Monday's game. He was hitless in three at-bats with a strikeout and a walk Monday.
"You really have to watch the player," Bochy said. "See how they handled it. I'm sure he's frustrated. But he's going out there and playing great defense. He's our first baseman.”