Carlos Beltran hit a pair of home runs and Tim Lincecum pitched seven strong innings as San Francisco extended its winning streak to four with a 3-1 victory over visiting San Diego on Wednesday afternoon.

The Giants trail Atlanta, also a winner Wednesday, by 6 1/2 games in the National League wild-card race. They began the day 8 1/2 games behind Arizona in the NL West.

Beltran hit a solo shot off Mat Latos (7-14) in the first inning to tie the game at 1-1, then added another blast to right field with one out in the sixth to give San Francisco the lead for good. The veteran outfielder came into the game with just three home runs in his first 117 at-bats with the Giants after coming over in a deadline deal with the New York Mets.

Mark DeRosa, the hero of Tuesday night's 12-inning Giants victory, tacked on an insurance run with a seventh-inning infield single.

Lincecum (13-12) gave up one unearned run in the first inning but was unchallenged the rest of the day, giving up just four hits and not allowing another runner past second base. He struck out six and walked two.

Santiago Casilla worked the ninth for his third save.

Latos pitched well in defeat, striking out eight while giving up three runs on seven hits in seven innings of work.