PITTSBURGH – When Jason Heyward and Andrelton Simmons each homered before the seventh pitch of the night, and the Braves had six runs before the Pirates batted, a four-game Atlanta winning streak and the end of an eight-game road skid seemed inevitable.

The Braves hung on, but it wasn’t quite as easy as might have been expected for Ervin Santana, who gave up three homers and didn’t make it out of the sixth inning of a 7-3 win at PNC Park to open a 10-game trip and three-game series.

“This is a carry over of the last five or six days when we’ve been playing good baseball,” said manager Fredi Gonzalez, whose Braves remained six games behind the surging National League East-leading Nationals and one game behind San Francisco for the second NL wild card slot.

“The season is ebbs and flows. Hopefully we’re on the top of one and we can ride it out for a little bit.”

For the Braves it’s been more like extreme highs and lows. Inconsistent and unpredictable all season, they were coming off a 6-4 homestand that concluded with a three-game weekend sweep of American League power Oakland, after an 0-8 West Coast road trip that was the worst for the Braves franchise since 1949.

“It’s good to keep the streak going at the moment, and it’s good to win the first game of a series,” said Heyward, whose third leadoff homer of the season sparked the Braves to their fifth inning of five or more runs this season. “It’s huge, man. It gives our pitcher that much more breathing room, a lot more room for error.

“It’s nice to get everybody in the game. I know we didn’t score a whole lot the rest of the way, but still, that’s a lot of pressure for a team to come back against.”

They staked Santana (13-6) to a big early lead the likes of which Atlanta pitchers have seldom experienced this season.

Santana gave up nine hits and two walks with four strikeouts in 5 1/3 innings, but the only runs he allowed came on homers –two by Starling Marte, one by Neil Walker — as the veteran improved to 6-0 with a 2.93 ERA in his past seven starts. He got a big assist from reliever Luis Avilan on an inning-ending double play with two in scoring position in the sixth.

“I didn’t have my stuff today,” Santana said. “But for me it was one of my best games. Because I gave up three runs, and when you don’t have your best stuff and you give up (only) three runs, that’s huge. Three solo homers, it doesn’t hurt. I just have to thank my teammates. They scored earlier and we got the win.”

Pirates starter Vance Worley (5-3) allowed only six earned runs in 27 innings this season at PNC Park before giving up five earned in the first inning. The Braves also knocked him around last season when he was with the Twins, and in 2012 when he was with the Phillies.

“The pitch I hit out, I was able to look at it (later) — it wasn’t a bad pitch,” said Heyward, who hit his 10th homer on a 90-mph fastball with the count 1-1. “He hit his spot. After that, we just kind of ran into some barrels. We had some good swings. We went up there confident. Once one guy saw it were were like, OK. We went up there to get something to hit, and we didn’t miss.”

After giving up five hits and two walks in the first inning, Worley limited the Braves to four hits over the next five innings, and they didn’t score again until Heyward’s bases-loaded sacrifice fly in the eighth off reliever John Axford. Worley had eight strikeouts in six innings.

“We had some good at-bats, back-to-back homers from the first and second hitters,” Gonzalez said. “I tell you what, having Jason up there at the top of that order, that’s a big presence. And we had some good at-bats in the first inning, then Worley kind of settled down and kept us off-balance the rest of the time. And Santana (gave up) three solo homers, two to Marte, and got himself out of some jams.

“Just from watching it on the jumbotron, the ball just kept coming back over the fat part of the plate (on the three homers off Santana).”

The Braves got two homers, a Freddie Freeman walk and consecutive singles from Justin Upton and Chris Johnson before Worley recorded an out. Johnson’s hit drove in the third run of the first inning. Gerald Laird’s one-out single pushed the lead to 4-0, and two runs scored when Santana hit into a potential double play and that turned a fielder’s choice when Walker’s throw to first sailed wide.

Heyward’s home run on the third pitch of the game was the sixth leadoff h omer of his career, and his fourth homer in 24 games against the Pirates. Simmons followed three pitches later with another home run, the fifth time in franchise history that the Braves opened a game with consecutive homers and third time in the past 12 seasons.

Martin Prado and Nate McLouth did it in 2011, and in 2003 the Braves started a game against Cincinnati with three consecutive homers from Rafael Furcal, Mark DeRosa and Gary Sheffield, the second team in major league history to accomplish that feat.

The six runs in the inning were one shy of the season-high seven the Braves scored June 10 at Colorado, also in the first inning.

After the Pirates cut the lead in half with three solo homers, a crowd of 31,669 got excited in the sixth inning when Santana allowed consecutive doubles to Marte and Travis Snider to start the inning and bring the potential tying run to the plate. (Marte didn’t score on Snider’s double, which was misplayed by center fielder Emilio Bonifacio, who got turned at the warning track.)

After Santana struck out Brent Morel, Avilan entered and fell behind 3-0 against pinch-hitter Ike Davis before getting him to line out to third base to start an inning-ending double play that preserved the 6-3 lead.

After allowing only one homer in 40 innings over his six-start unbeaten streak before Monday, Santana gave up a pair of leadoff homers to Marte in the second and fourth innings and a third-inning homer to Walker that bounced into the Allegheny River beyond the right-field seats. It was the 35th ball to reach the water since the ballpark opened, and the first this season.

He got into a few other tight spots, but Santana worked out of them by limiting the Pirates to one hit in six at-bats with runners in scoring position, and that hit was Marte’s double that could just as easily have been ruled an error on Bonifacio.