The NL West-leading Giants have won four straight and eight of nine. The Braves, who lead the NL East, have lost five straight, their longest skid in two years.
The Giants have hit homers in 10 straight games, matching their longest run in almost four years.
The Giants got only four hits. They scored all their runs on homers for the second straight night after hitting two homers in Friday night’s 2-1 win.
Ryan Vogelsong (1-1) allowed one run on five hits and four walks in six innings.
Julio Teheran (2-2) gave up just four hits with no walks in seven innings, but allowed a season-high three runs.
Sergio Romo pitched a perfect ninth for his ninth save. Jeremy Affeldt and Jean Machi also pitched scoreless innings in relief.
Belt did not start in Friday night’s game and was in a 1-for-21 slump with 12 strikeouts before he led off the second inning with his eighth homer.
The Braves’ only run came in the third. Jason Heyward walked, stole second and scored on B.J. Upton’s double to the left-field wall.
Posey homered in the fourth for a 2-1 lead. His seventh homer landed in the first row behind the left-field wall.
Morse led off the seventh with a towering drive into the seats in left-center. He has five homers in his last 10 games, including back-to-back games against the Braves.
The Braves’ hitting woes continued. They were held to one run by Giants pitching for the second straight game and have scored no more than one run in 11 of 29 games this season.
“We’ve got too much talent offensively,” Braves manager Fredi Gonzalez said before the game. “We shouldn’t be scoring one run, two runs or three runs.”
Each team wore Negro Leagues throwback uniforms for the Heritage Game — the Atlanta Black Crackers and the 1946 San Francisco Sea Lions. Each ensemble featured high socks.
NOTES: The last time the Giants hit homers in 10 straight games was from Sept. 23-Oct. 3, 2010. ... Of Belt’s eight homers, seven have come on the road. ... Atlanta’s last five-game losing streak was May 21-28, 2012. ... Gonzalez said he expects to announce a roster move on Sunday to clear a spot for RHP Gavin Floyd, who has completed his rehab from 2013 elbow surgery while with the White Sox. Floyd’s role has not been revealed. ... The series concludes today when Atlanta’s Alex Wood faces San Francisco’s Madison Bumgarner in a matchup of left-handers.