The Giants, playing virtually the entire season without injured closer Brian Wilson and the stretch run without the suspended Melky Cabrera, have their biggest division lead since 2003 and have won seven of their last 10 games against the Dodgers.
Meanwhile, the Dodgers are 5-8 since completing the blockbuster trade with the Red Sox that was designed to ensure a postseason appearance. At the end of May they led by 7 1/2 games.
"No matter how good you are on paper," said Victorino, "it doesn't mean you go out and win the games."
Despite Lincecum walking a career-high seven in 6 1/3 innings, the Dodgers went 0-for-10 with runners in scoring position and stranded 11. Batters two through six -- Victorino, Adrian Gonzalez, Matt Kemp, Hanley Ramirez and Andre Ethier -- went a combined 0-for-20. Kemp had the only RBI in the bunch on a groundout.
Adam Kennedy, earning a rare start at third base, padded his stats against Lincecum with a go-ahead homer in the sixth inning. But he also injured his right groin muscle on defense in the bottom of the inning and could be lost for the rest of the season.
Mark Ellis and A.J. Ellis did the rest of the heavy lifting for the Dodgers with a pair of hits each, A.J. Ellis also walking twice and Mark Ellis once.
"They wouldn't be human if they didn't feel the pressure, but we've gotten chances and haven't been able to get the big hit in a major way," said manager Don Mattingly. "We've got a chance to win tomorrow and win the series Sunday. That's what we came here to do. The middle game will be a big game for us."
Chris Capuano, 2-7 over the last two months and 1-6 lifetime against the Giants, starts for the Dodgers on Saturday against Giants ace Matt Cain.
"We just need to keep going, that's all I can say," said Lincecum. "I don't think anybody in this room is saying that's enough room right now with the time we've got left. We need to keep pushing and not give in."
Journeyman Marco Scutaro, picked up by the Giants while the Dodgers were buying up superstars, won the game with a two-run broken-bat single in the bottom of the seventh inning to chase Beckett, who was never hit hard by the Giants despite allowing four earned runs in 6 1/3 innings.
The Dodgers were befuddled by Lincecum, who relied on his changeup and, like Beckett, rarely threw harder than 91 mph.
Hector Sanchez led off the decisive bottom of the seventh with a single to right. Pinch-runner Gregor Blanco stole second and Brandon Crawford walked on four pitches. Pinch-hitter Emmanuel Burriss bunted the runners to second and third. Angel Pagan was walked intentionally to load the bases.
With Brandon League in the bullpen, Mattingly went to the mound to be sure Beckett wanted to continue. With the infield defense at double-play depth, Scutaro dunked the two-run single off the end of the bat into right field.
The Dodgers scored in the third inning off Lincecum, who didn't get any help from his defense. Mark Ellis led off with a single and Victorino walked. Gonzalez hit a double-play ball to second baseman Scutaro, who bobbled the ball and settled for the out at first.
With runners on second and third, Kemp grounded to third baseman Pablo Sandoval, who also bobbled the ball and settled for the out at first as Ellis, breaking from third on contact, scored.
The Giants answered in the bottom of the inning. With one out, Crawford singled, was bunted to second by Lincecum and was singled home by Pagan. Scutaro singled Pagan to third, but Sandoval lined a rocket into shortstop Ramirez's glove to end the inning.
With two out in the sixth inning and an 0-2 count, Kennedy homered off Lincecum. Kennedy was getting a rare start in place of third baseman Luis Cruz because he came into the game with a .381 lifetime average against Lincecum. Cruz had started the previous eight games.
Beckett again gave up the lead in the bottom of the sixth on a pair of infield singles. Pagan bunted for one of them, stole second and went to third on Sandoval's grounder. After Buster Posey walked, Hunter Pence topped a chopper that took a sideways bounce past Kennedy, who was injured on the play.