"I didn't know he was going to hit the way he has hit," Halladay said, "with the power that he has."
Kratz homered in the ninth inning off Braves closer Craig Kimbrel and John Mayberry Jr. hit a three-run shot off Cristhian Martinez in the 10th to help the Philadelphia Phillies rally for an 8-5 victory over Atlanta on Friday night.
Josh Lindblom (3-3) pitched a scoreless ninth, allowing one walk and striking out one.
Martinez (5-4) allowed three hits, three runs, one walk and struck out two.
The Braves, who have lost two straight and three of four, dropped 6 1/2 games behind first-place Washington in the NL East.
Philadelphia has won two straight and six of eight. The Phillies are 18 games back in the NL East, but they finished August with a 17-12 record.
"I've got a headache," Phillies manager Charlie Manuel said while a smile as he shook a bottle of aspirin. "It was a mentally tough game. It's amazing. It's unreal. Good game. Good comeback win."
Kevin Frandsen led off the 10th with a single, moved to second on Martinez's balk and advanced to third on Chase Utley's groundout. After Ryan Howard was intentionally walked, Martinez struck out Juan Pierre before Mayberry's 13th homer landed in the seats in left field.
Kratz's homer made it 5-all in the ninth. The save opportunity was just Kimbrel's third since Aug. 3. Though Kimbrel has converted 32 of 35 chances this season, his last blown save came July 20 on a homer by Washington's Danny Espinosa.
Kratz finished the game 3-for-5 and has hit safely in 15 of his 25 starts. With Ruiz hopeful to come back soon from the disabled list, Kratz might hope the Phillies remember that 15 of his 27 hits this year are for extra bases.
"You can't say enough about Kratzy's at-bat," Mayberry said. "Kimbrel's obviously one of the best closers in the game. For him to come up with a clutch hit like that was huge and kind of put the momentum on our side."
Uggla homered off Jeremy Horst to break a 4-all tie in the sixth.
Howard, whose 10th homer made it 1-0 in the second, cut Atlanta's lead to 4-3 in the sixth with a two-run single that chased Atlanta starter Mike Minor. Ty Wigginton's sacrifice fly off Chad Durbin made it 4-all.
Halladay gave up seven hits, four runs, four walks and struck out three in 4 2-3 innings.
Halladay is 0-3 with a 6.75 ERA in four starts at Turner Field this year. The two-time Cy Young Award winner had gone 4-1 with a 2.75 ERA in his first five August starts.
Not until the third inning did Halladay tell anyone that he had been sick the night before. He delivered the news to pitching coach Rich Dubee.
"I didn't feel very good last night," Halladay said. "I was just zapped once I got out there. I tried to battle as much as I could. I just didn't have enough there by the fifth inning."
The Phillies have won just two of their last nine against Atlanta.
Minor led off the fifth with a single and scored with one out on Prado's eighth homer. After Jason Heyward's popup, Hallaway walked Chipper Jones before Freeman launched his 19th homer to make it 4-1.
In the sixth, Minor loaded the bases on singles by Jimmy Rollins, Frandsen and Utley. Howard singled softly to centre to score Rollins and Frandsen and cut the lead to 4-3.
"It's obviously not a good thing," Minor said. "If they give me runs, I need to go out there and shut that inning down. But it's obviously disappointing to give up some base hits right there and pretty much all the runners score."
Howard has 40 homers and 115 RBIs in 129 career games against Atlanta.
Minor allowed seven hits and four runs with one walk and three strikeouts in four-plus innings.
On the last play of the fourth, the 40-year-old Jones was trying to score from second on Janish's single to centre, but he was tagged out at the plate by Kratz. Though Jones lowered his shoulder and knocked Kratz on his back, Kratz held onto the ball to preserve Halladay's 1-0 lead.
"He got him good," Halladay said. "It was a big play. Knowing you're going to get hit like that and still catching the ball, it takes some toughness."
Notes: Braves SS Andrelton Simmons has been cleared by a team physician to begin baseball activities and could start a rehab assignment on Tuesday. ... Rollins apologized to Manuel before the game and returned to the lineup a day after the former NL MVP was benched in the middle of a game for failing to hustle. ... Minor went 1-1 with 2.40 ERA in his first two starts against the Phillies this year. ... The Braves released SS Jack Wilson before the game and later announced a trade with Detroit for utility man Jeff Baker.