ATLANTA — Evan Gattis kept up an amazing rookie season with his first grand slam, B.J. Upton and Ramiro Pena also homered, and the Atlanta Braves finished off a sweep of the woeful Minnesota Twins with an 8-3 rout on Wednesday.

The Braves stretched their winning streak to six games with a second straight series sweep, making things easy for starter Paul Maholm (6-4). The left-hander held the Twins to an unearned run in 7 1-3 innings.

With the Braves already leading 4-0, Gattis struck again less than 24 hours after his two-out, pinch-homer in the ninth allowed the Braves to pull out a 5-4 win over the Twins in extra innings.

He was swinging away on a 3-0 pitch with the bases loaded in the fourth and launched an opposite-field drive just inside the right-field pole for the 10th homer of his improbable debut season.

As Gattis rounded the bases, the theme from “The Natural” played over the speakers at Turner Field. In the Atlanta dugout, Upton looked on in disbelief, both arms in the air as if to say, “Is this really happening?”

Believe it. The 26-year-old Gattis made the team as a non-roster player in spring training after quitting baseball during college, working a variety of odd jobs, and dealing with bouts of depression that had him contemplating suicide. He still has a picture of his ID card from working as a janitor on his Twitter page.

He eventually returned to baseball after completing a spiritual journey. He got extensive playing time in April while the Braves battled injuries, earning the NL rookie of the month honors, and he’s making the most of his more limited chances in May.

Gattis’ dramatic homer Tuesday was his third as a pinch-hitter, and it was the fourth time he’s hit a tying or go-ahead homer in the eighth inning or later. He got the start at catcher for the series finale, giving Brian McCann the day off.

Vance Worley (1-5) had another dismal outing for Minnesota, failing to make it through the fourth as the Twins lost their eighth in a row. He surrendered eight runs and 10 hits in 3 2-3 innings, also hitting two batters and walking two more. His ERA climbed to 7.21, and it would have been worse if Pena had not been thrown out at the plate in the first attempting to score on a flyout to left fielder Josh Willingham.

Immediately after the game, Worley was demoted to Triple-A Rochester.

Before leaving, Worley’s horrendous problems in the first continued when he surrendered two hits and a walk, including Jason Heyward’s run-scoring single. In 10 starts, the right-hander had allowed 17 runs and 24 hits in the opening inning.

Atlanta made it 3-0 in the third. Pena hit his second homer of the season and, after Worley plunked a pair of hitters, Chris Johnson came through with a two-out single to bring in another run.

The Braves blew it open in the fourth. Upton, hitting just .153 coming in, led off with a homer into the seats in left-center. After Maholm’s flyout, Jordan Schafer singled, Heyward singled, Freddie Freeman walked and Gattis went deep to finish off the Twins.

Minnesota’s only run off Maholm came after Johnson’s error at third base set up Justin Morneau’s RBI single in the sixth.

Aaron Hicks and pinch-hitter Oswaldo Arcia homered in the ninth off Cory Rasmus, making his major league debut.

NOTES: The Twins placed 3B Trevor Plouffe on the seven-day DL with a concussion. He took a blow to the head in the 10th inning of Tuesday night’s game while breaking up an attempted double play. … Minnesota called up former independent league star Chris Colabello, who was batting .358 at Triple-A Rochester and leading the International League with 12 homers and a .659 slugging percentage. Colabello got the news after midnight on a bus ride from Allentown back to Rochester, just made an early morning flight to Atlanta and was in the lineup for the 12:10 p.m. start, playing right field and batting sixth. He went 0 for 4 with two strikeouts. … The Braves already have swept five series this season. … Rasmus is the younger brother of Toronto OF Colby Rasmus.