CHICAGO  — Justin Germano's shaky first inning put the Cubs behind right away and with San Francisco's Tim Lincecum pitching, it meant another loss for Chicago in this dismal season.

Germano retired the first two batters of the game before giving up singles to Pablo Sandoval and Buster Posey, walking Hunter Pence and hitting Hector Sanchez with a pitch to force in the first run.

Xavier Nady, who was once Germano's minor league roommate, then hit a hard shot past third for a three-run double and the Giants had four quick runs on their way to a 5-2 victory.

"The thing just snowballed out of control," Chicago manager Dale Sveum said of the first inning as Chicago dropped to 30 games under .500 at 51-81.

Nady, who once played with the Cubs, made an impact in his first at-bat for the Giants after  being called up from Triple-A when rosters expanded Saturday.

"He's a good hitter and you definitely have to mix it up with him because he can hurt you with the long ball and hurt you with the drives in the gaps," Germano said. "He's strong, he's always been strong."

San Francisco made it 5-0 in the second on Angel Pagan's triple and Marco Scutaro's sacrifice fly.

Lincecum allowed just four hits over 6 1-3 innings, benefiting from the early run support.

"It's always nice, especially when you've got a guy like Lincecum on the mound. I was fortunate to come up with an opportunity to come up with a big hit. It was pretty neat," Nady said.

Lincecum, who won back-to-back Cy Young awards in 2008 and 2009, allowed two runs on David DeJesus' seventh homer and struck out seven. He walked three.

"That's not the same guy we saw winning Cy Youngs. The command, the velocity with the fastball, that's completely different than it was a few years ago," Sveum said. "He knows how to get through lineups with his off-speed stuff, his changeup, his curveball."

Germano (2-5) allowed six hits in five innings while throwing 93 pitches.

Sergio Romo, the fourth Giants reliever of the day, pitched the ninth for his ninth save in 10 chances.