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09/09/09 2:54 AM ET

Bumgarner solid, but Giants lose ground

San Francisco falls three games back in Wild Card race

SAN FRANCISCO -- Tuesday was a good day for the Giants' future. Their present-day prospects, however, dimmed somewhat.

Making a surprise start for Tim Lincecum, who was scratched with back spasms, Madison Bumgarner displayed his heralded potential while surrendering two runs in 5 1/3 innings. Bumgarner left with a one-run lead and a chance for a victorious Major League debut. But San Francisco's usually reliable bullpen softened in a 4-3 loss to the San Diego Padres that dented the Giants' postseason hopes.

First-place Los Angeles moved 6 1/2 games in front of the Giants in the National League West standings while Wild Card leader Colorado stretched its edge over San Francisco to three games. The upcoming three-game series at AT&T Park against the Dodgers this weekend and the Rockies immediately following that loom even larger.

"Any time you lose at this stage, it's going to be a tough loss," catcher Bengie Molina said.

Fortunately for the Giants, Lincecum's ailment isn't considered serious.

"It's encouraging for us that he's probably going to [make] his next start. We need him on the mound," said Molina, sounding privy to inside information.

Giants manager Bruce Bochy wasn't certain when Lincecum will pitch again, but relayed the athletic training staff's postgame report.

"He's making a lot of progress," Bochy said. "He feels much better. That's good news for us. Hopefully this continues and tomorrow he comes in and says he's ready to go. But we'll wait and see here the next day or two."

The Giants also received consolation from Bumgarner, who has been viewed as a worthy counterpart to Lincecum, Matt Cain and the rest of San Francisco's starting rotation. He just wasn't expected to arrive in San Francisco this soon.

The Giants had taken a deliberate approach with Bumgarner, leaving him at low-Class A Augusta all last year and advancing him only to Double-A Connecticut this season while he ran his two-year Minor League record to 27-5. He was preparing to pitch Connecticut's Eastern League playoff opener Wednesday when the Giants told him Monday night to report to San Francisco.

And once Lincecum was deemed unavailable, the Giants made Bumgarner, at 20 years and 38 days old, the franchise's youngest pitcher to start a game in his Major League debut since it moved west in 1958 (Mike McCormick started for San Francisco as a 19-year-old, but made his debut two years earlier when the team called New York its home). At around 3:30 p.m. PT, with Lincecum's name still on the lineup sheet posted in the clubhouse, Bochy called Bumgarner into his office to inform him he would start.

"I got here and I was just excited to be here and be a part of this. Then I found out I was pitching, and [that] made it even more crazy," said Bumgarner, whose temporary nameplate above his dressing stall read "BUMGARER."

Bumgarner didn't disappoint. Demonstrating an affliction common to many inexperienced pitchers, he allowed home runs to Chase Headley in the second inning and Kevin Kouzmanoff in the fourth. Otherwise, Bumgarner permitted just one runner to reach scoring position.

"He didn't rattle at all," Molina said.

"That's definitely the most fun I've had in a long time," Bumgarner said.

If the AT&T Park patrons were disappointed by Lincecum's absence, they didn't show it. They cheered noisily when Bumgarner was introduced in the starting lineup, roared when he flung a called strike past Everth Cabrera on his first Major League pitch and gave him a standing ovation when he returned to the dugout after his three-up, three-down, 14-pitch first inning.

"These are the best fans in the world," Bumgarner said. "They just embrace you when you come here. I didn't think anybody was going to know who I was, but it seemed like everybody did."

The only oddity of Bumgarner's effort was his diminished velocity. Having dominated opponents with a fastball that reached 95 mph, he topped out at around 90 mph against the Padres.

"It feels the same coming out. It's just not reading on the radar gun," said Bumgarner, sounding not the least bit surprised at the question. "I guess [I'm] maybe getting a little tired. I don't feel it, but I guess that's what's happening."

Locked in a 2-2 tie, the Giants forged ahead in their half of the fourth as Aaron Rowand, who homered in the second inning, singled, advanced on a groundout and scored on Eugenio Velez's two-out single.

But San Diego pulled even in the seventh and denied Bumgarner a win as Will Venable homered off Brandon Medders.

The Padres didn't stop there. Adrian Gonzalez opened San Diego's eighth against Jeremy Affeldt (1-2) by smashing a grounder off third baseman Juan Uribe's glove for a single. Gonzalez advanced to second base on Kouzmanoff's single and scored on Headley's single as Molina couldn't hold on to a strong throw from right fielder Nate Schierholtz.

"I thought [Gonzalez] was going to be safe anyway," Molina said. "I tried to be too quick. I had to go forward to get the ball because the throw wasn't right on top of the plate. I didn't want to get it on the short hop, so I tried to get it in the air and go back and be quick."

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.