PHILADELPHIA – After seeing the Braves repeatedly fail with runners in scoring position Monday night, Evan Gattis left nothing to chance in the late innings when he hit a pair of home runs that provided a two-run lead for Ervin Santana against the Phillies.

Then Dan Uggla and Andrelton Simmons followed Gattis’ eighth-inning leadoff homer with longballs of their own, and those three consecutive home runs turned what had been a one-run lead into a 5-1 bulge. More than enough for the Braves bullpen, right?

Well, no. It wasn’t.

But after reliever Luis Avilan melted down in a five-run eighth inning that gave the Philllies a 6-5 lead, Uggla came through with the biggest hit of the night, a grand slam with one out in the ninth inning for a rollicking 9-6 Braves win in a series opener at Citizens Bank Park.

The Braves have a four-game winning streak and have racked up 15 home runs in their past six games

“We have a lot of guys who can change the game with one swing,” Uggla said. “It’s just a matter of if we do it or not. Tonight we were able to put some at-bats together. We didn’t have much going on early, but we ended up getting to them and were able to come out of there with a win.”

After Gattis struck out with the bases loaded in the ninth, Uggla slammed left-hander Jake Diekman for the 19th multi-homer game of the second baseman’s career. He cleared the bases with a homer over the left-center fence on an 0-1 slider.

“He threw a fastball first pitch and I was kind of, like, oh, man, this is going to be tough,” said Uggla, who took that pitch for a strike. “But then he threw a slider, and luckily I just got enough of it.”

The Phillies’ five-run eighth against Avilan was fueled by a leadoff walk and four hits, Domonic Brown’s three-run homer to the right-field seats before Avilan had even recorded a second out. Braves manager Fredi Gonzalez revealed after the game that closer Craig Kimbrel was resting a sore shoulder and unavailable to pitch Monday.

Kimbrel and Gonzalez both characterized the soreness as typical sort of discomfort that any pitcher goes through during the course of a season, and Kimbrel said he should be ready to pitch after a few days’ rest.

“Nothing major, just no reason to push it this early in the year,” said Kimbrel, who last pitched Saturday, when he recorded his majors-leading fifth save. “Take a few days off, be ready to go.”

Overshadowed by the late-innings rollercoaster was another stellar performance by Santana, who matched a career high with 11 strikeouts in six innings while allowing four hits, two walks and one run in his second start for the Braves.

“I feel great, that’s the main thing,” said Santana, who is 1-0 with an 0.64 ERA, 17 strikeouts and two walks in 14 innings. “I was throwing a lot of strikes and keeping the ball down for the most part. Everything was good for us – defense, offense, so … what else do you need?”

Said Uggla: “We’re so glad he’s on our team. He comes out and does his thing, focused, takes if very seriously. He was electric tonight.”

Gattis’ two-run homer in the sixth and leadoff homer in the eighth gave him four homers in his past two games at Citizens Bank Park, where the catcher nicknamed El Oso Blanco has become something of a Broad Street Bully against the Phillies. Before Monday, his only other two-homer game was against Cole Hamels on Sept. 8 at Philadelphia.

All of Gattis’ four career hits at Citizens Bank Park have been home runs, in 20 at-bats and five games.

“He had a great at-bat and gave us the lead early on, then came up again and did it again,” Uggla said. “It’s always fun to see big man hit it hard like that.”

Gattis hit an opposite-field home run to the right-field seats against veteran Roberto Hernandez in the sixth, and combined with Uggla and Simmons for the three consecutive homers off right-handed reliever B.J. Rosenberg in the eighth.

Gattis has six home runs among his 11 hits in 11 career games against the Phillies – twice as many homers as he’s hit against any other team. He has three home runs in nine games this season, after ranking second among major league rookies with 21 homers in 2013.

Simmons has home runs in consecutive games for the Braves, who have hit 14 homers in their past six games.

Until Uggla’s grand slam, the Braves were 0-for-10 with runners in scoring position. And after they stranded runners at third base in each of the first two innings, Ryan Howard gave the Phillies a 1-0 lead with his line-drive home run leading off the second inning.

But the Phillies also wasted a few scoring opportunities and eventually saw Santana settle into a groove.

After major league batting leader Chase Utley extended his hitting streak to 11 games with a one-out double in the sixth inning, Santana struck out Howard and Byrd, giving him five strikeouts against the last seven batters he faced. He was replaced after throwing 96 pitches (63 strikes).

“I’ve been so impressed with him, being able to mix his pitches,” Gonzalez said, “and by the way, it’s still 93, 94 mph. And he’s got command, he’s got some life, he’s got some other stuff. He knows how to pitch. I’ve been really happy with him.”

Gonzalez pulled Santana after 88 pitches Wednesday in eight scoreless innings against the Mets, who provided a scare by scoring three runs against the bullpen in the ninth inning of a 4-3 Braves win. Gonzalez said he would be careful early with Santana, since he missed three weeks of spring training and made only four starts (instead of the customary six) before his regular-season debut.

He said they’d probably add another 10-15 pitches on Santana’s limit in the next start for the right-hander.

The Braves had a chance to take an early lead Monday. Jason Heyward hit a broken-bat single on the first pitch of the game. After grounding into a fielder’s choice, B.J. Upton stole second and advanced to third on catcher Cody Asche’s throwing error. But Hernandez got out of trouble by striking out two of baseball’s other hottest hitters, Freddie Freeman and Justin Upton.

The Braves stranded runners on the corners in the second inning, after Simmons hit his second triple in as many days. He hit the 10th pitch with two out, a long fly ball that glanced off the glove of center fielder Tony Gwynn Jr., near the outfield wall as he raced back for the catch attempt.

Ramiro Pena then walked on five pitches to bring up Santana, who grounded out on a comebacker to Hernandez.

The Braves’ third inning nearly mirrored the first in its setup, with them getting a runner to third base with one out and again failing to score. This time Heyward walked, stole second – his fourth steal – and advanced to third on B.J. Upton’s groundout.

Freeman was up again with a runner at third. He hit a sharp grounder to Hernandez that resulted in an inning-ending double play when Heyward was caught in a rundown and Freeman was thrown out trying to advance to second on the play.

The Braves also failed to score in the fifth after putting a runner in scoring position with less than two out. Ramiro Pena lined a one-out double to the right-field corner, but Santana grounded out to the shortstop. After putting Heyward on base with a four-pitch walk, Hernandez induced an inning-ending groundout from B.J. Upton.