Freddie Freeman had three RBIs as the Braves chased Roy Halladay in the fourth inning. Upton belted a two-run shot in the first to give him a pair of homers in his first two games for Atlanta.
Halladay (0-1), who struggled with a sore shoulder last season and had a difficult spring training, gave up five runs and six hits in 3 1/3 innings. The two-time Cy Young Award winner struck out nine, but dropped to 0-4 with an 8.00 ERA in his last seven starts against Atlanta.
The game was played in a steady drizzle, but the conditions hardly affected Paul Maholm (1-0), who allowed six hits in 5 2/3 scoreless innings. He struck out six and walked one.
Gattis led off the fourth inning of his first major league game with a drive to left. Maholm struck out, but Halladay’s night was over after he issued a walk to Andrelton Simmons.
Raul Valdes came in and walked the next two batters before Freeman hit a bases-clearing double to make it 7-0. Freeman has driven in six of Atlanta’s 16 runs in the first two games.
Maholm struggled last year against Philadelphia with an 8.64 ERA in two starts. But the left-hander stranded runners in scoring position in three of the first four innings in his first start of 2013.
Cory Gearrin replaced Maholm with a runner on first in the sixth. He walked one before striking out Erik Kratz.
The Phillies were just 1-for-11 with runners in scoring position.
Juan Francisco also singled in a run in the first as Atlanta quickly built a 3-0 lead.
Halladay recorded his first eight outs on strikeouts, but he needed 79 pitches to make it through the first three innings. He was trying for win No. 200 and a spot alongside New York Yankees left-hander Andy Pettitte as the only active pitchers to be 100 games over .500.
Heyward tacked on a two-run homer against Jonathan Papelbon in the eighth.
Chase Utley had a two-run double in the seventh for Philadelphia. Utley appeared to score a third run in the seventh, but home plate umpire Mike Everitt called Michael Young out for runner’s interference at first and the inning ended.
NOTES: The Braves struck out 16 times. ... Freeman has reached in six of his eight plate appearances this season. ... Philadelphia SS Jimmy Rollins played his 1,794th game to tie Richie Ashburn for second place on the Phillies’ career list. ... Braves CF B.J. Upton went 0-for-4 and has struck out in his last five at-bats. ... Phillies 1B Ryan Howard is 0-for-8 with three strikeouts. ... Gattis became the first Brave since Heyward in 2010 to homer in his first big league game. ... Braves manager Fredi Gonzalez said C Brian McCann, on the 15-day disabled list recovering from shoulder surgery, will return to the team’s complex near Orlando today to resume his rehab. Gonzalez did not know when McCann can resume baseball activities. ... The Phillies dropped to 2-6 in their last eight games at Turner Field. .. Philadelphia claimed OF Ezequiel Carrera off waivers from Cleveland and made room for him on the 40-man roster by designating OF Ender Inciarte for assignment.