Philadelphia is also just one game behind the NL East-leading New York Mets, who fell to the Atlanta Braves, 7-4, earlier in the day.
In the opener, Burrell snapped out of a recent slump with two hits, including the go-ahead single in the eighth inning, and the Phillies won 7-3.
Pitching on three days rest for the first time since Oct. 3, 2004, against Florida, Myers (10-11) gave up just a pair of hits while striking out four. Myers, who tossed his second complete game in a 95-pitch performance, is 7-2 in 11 starts since being recalled from the minor leagues on July 20. Myers also threw a complete game in a 4-0 win over Washington on Aug. 20.
Prince Fielder hit a solo homer for the Brewers, who have lost four straight and 11 of 14.
Philadelphia jumped out to a 6-0 lead with one run in the first, three in the second and two in the fourth.
With runners on first and third in the second, Myers helped himself with an RBI single to right, scoring Burrell. Myers was 3-for-53 this season before his at-bat and he picked up his first RBI in more than two years. Myers' last one came against Washington on May 30, 2006.
Jimmy Rollins followed with a two-run single, scoring Chris Coste and Myers, who barely eluded the tag of Milwaukee catcher Jason Kendall at home.
Burrell's 31st homer, a solo blast in the fourth off Jeff Suppan, pushed the lead to 5-0. Suppan later walked Jayson Werth with the bases loaded, scoring Victorino for the sixth run. Suppan (10-9) labored through 3 2-3 innings, giving up six runs and eight hits.
In the opener Sunday afternoon, Burrell singled to cap a four-run eighth inning.
"It's big. I can't lie," said Burrell, whose average had dipped to .250 before Sunday's first game. "I needed to get a hit in a situation with the game on the line."
Ryan Howard hit his major league-leading 44th home run and Victorino also connected as the Phillies beat the Brewers for the third straight time.
The Brewers are trying to avoid a repeat of last year's late collapse, when they built an 8½-game lead in the NL Central in late June only to finish two games behind the Chicago Cubs.
"When you're struggling, things never seem to go your way," Milwaukee manager Ned Yost said.
It was 3-all when Jayson Werth led off the Phillies eighth with a single against Guillermo Mota (5-6). Chase Utley followed with a sacrifice bunt and Howard was intentionally walked before Burrell singled off Brian Shouse. Victorino then hit a three-run homer to give the Phillies a cushion.
"Every night, there's somebody else picking us up," Victorino said. "That's how you win a pennant."
Scott Eyre (4-0) got two outs for the victory. Mota had his scoreless innings streak snapped at 14 1-3, spanning 16 appearances.
Joe Blanton overcame a shaky start to toss seven effective innings for Philadelphia. He gave up five hits and three earned runs and still has not lost since the Phillies got him from Oakland on July 17 - he's 2-0 over those 11 starts.
"I just tried to be aggressive," Blanton said. "I left a couple balls over the plate in the first inning and the guys had good swings on me."
Notes: In the opener, Hart thwarted a Phillies rally with a terrific catch in right field to end the fifth. Werth lofted a towering fly ball and Hart seemed to lose the ball in the sun before locating it and making a difficult catch as he fell to the ground. ... Utley was hit by a pitch for the 26th time, setting a team record. He leads the majors this year in HBPs. ... This was the first doubleheader featuring the Phillies and Brewers. Game 1 drew a crowd of 43,950, the 47th sellout this season. Game 2 attracted 39,776, just shy of a sellout.