Gattis took advantage of some last-second tips from teammate Justin Upton before hitting a go-ahead, two-run homer off Kenley Jansen in the eighth inning, and the Atlanta Braves rallied to beat the Los Angeles Dodgers 3-1 on Saturday night.
Andrelton Simmons followed Gattis with another homer off Jansen after each listened to quick reminders from Upton on the right-hander's signature cutters.
"I remembered (Upton) said something about (Jansen) in the advance meeting, so I wanted to go to him to see what I could get," Gattis said. "Whatever I could get in an at-bat like that was going to help."
Gattis said Upton's advice was to avoid cutters that appeared to be bound for the middle of the plate, because they would break off the plate. Gattis said Upton's instruction was to wait on a pitch "starting at you, or it looks like it's starting at you. That's going to be the one that you want."
Gattis fouled off two cutters before hitting the line-drive homer.
Jansen (1-2) said Gattis "just hit a good pitch."
"What could I do?" Jansen asked. "I'm not going to let that bother me. Tip your hat. He hit a good pitch. You've got to go in there. Period. He's creeping up on home plate every time I'm throwing outside. I put it where I wanted to put it."
Gattis has eight homers and ranks third in the majors with six game-winning RBIs.
"Awesome," said Simmons of Gattis. "He's awesome. Just amazing. That's all you can say. Pretty much you saw it coming, but just seeing it is awesome. He's a great hitter. He's always ready to go and he's fun to watch."
Gattis, primarily a catcher, also has played left field and first base. The recent returns of catcher Brian McCann and right fielder Jason Heyward from the disabled list may make it difficult for Gattis to find regular playing time, but he said he enjoys pinch-hitting.
Braves manager Fredi Gonzalez sees a benefit in having Gattis available as a pinch-hitter.
"He likes these moments, it seems like," Gonzalez said. "It's almost better that you can put him in anywhere you want, but sooner or later we've got to get him three or four at-bats."
Kris Medlen, Cory Gearrin, and Craig Kimbrel combined on a two-hitter for Atlanta.
Chris Capuano led 1-0 before he allowed a one-out single to B.J. Upton in the eighth. Dodgers manager Don Mattingly brought in Jansen (1-2), the hard-throwing right-hander, to face Gattis even though Capuano had allowed just five hits and thrown only 91 pitches.
"I'm not going to let him lose that game," Mattingly said of Capuano.
Capuano said he told Mattingly after his last at-bat in the eighth inning to be prepared to pull him out of the game because he had lingering problems with a strained calf.
"It wasn't affecting pitch execution out there," Capuano said. "It just feels a little tired. I've got an extra day before the next start. With treatment and stuff we should be able to get that ready."
Gearrin (1-0) pitched a scoreless eighth in relief of Medlen, who gave up two hits and one unearned run in seven innings. Kimbrel pitched a perfect ninth for his 13th save.
The Dodgers, who have lost two straight to the Braves after winning four of five, scored their only run in the fourth. Adrian Gonzalez walked and scored on Skip Schumaker's double to the left-field corner and left fielder Justin Upton's fielding error. Schumaker wasn't given an RBI.
The only other hit allowed by Medlen was a second-inning single by Tim Federowicz.
"Medlen was outstanding," Gonzalez said. "He was ready for one of these games. You saw seven innings of him being the Medlen of last year."
Chris Johnson had three hits for the Braves, who won after finding themselves in a sudden bullpen crisis.
Before the game, Braves general manager Frank Wren said an MRI revealed a tear in Eric O'Flaherty's left ulnar collateral ligament in his elbow. O'Flaherty was placed on the disabled list and could face season-ending surgery.
On Thursday, left-hander Jonny Venters had Tommy John surgery for the second time, ending his season. On Friday, right-hander Jordan Walden was placed on the 15-day disabled list because of shoulder inflammation.
Medlen, who had been 0 for 13 this season, had a brief celebration in the third inning when he had a bloop single for his first hit. Standing and smiling on first base, Medlen lifted his hands to the sky before giving first-base coach Terry Pendleton a hug.
Dodgers center fielder Matt Kemp leaped and reached over the wall to take a home run away from Heyward in the first inning. Heyward took off his helmet while crossing second base. Just when it appeared he might toss the headgear in disgust, Heyward instead lifted the helmet toward Kemp in a gesture of respect.