Morgan (1-0, 3.94 ERA) said he thought he did a better job of putting hitters away when he was ahead in the count.
"I missed one with [Ender] Inciarte, but other than that, I feel like I corrected it a little bit," he said.
Morgan struggled against the Braves in the past, entering Tuesday's game 0-3 with a 4.00 ERA against Atlanta. He tied a career-high by lasting seven innings, throwing 90 pitches.
"We thought about letting him go back out there [to pitch the eighth inning], but his previous two outings were not real good," Phillies manager Pete Mackanin said of Morgan, adding that he wanted him to go into his next start having accomplished seven solid innings.
The lone run Morgan allowed came in the fourth inning with runners on first and third and nobody out. He induced Atlanta catcher Tyler Flowers into a 6-4-3 double play, trading two outs for a run that tied the game 1-1.
Maikel Franco provided what would end up being a key insurance run with a solo homer to left -- his seventh of the season -- to lead off the eighth inning.
"I knew this team was exciting in Spring Training," Morgan said. "Those guys, everybody's got a lot of energy."
Aimee Sachs is a contributor to MLB.com based in Atlanta. This story was not subject to the approval of Major League Baseball or its clubs.