Estrada (4-6) allowed three hits and retired the last 10 batters he faced in improving to 4-1 with a 1.23 ERA in his last six starts. He struck out four and walked one.
"We're just having a lot of fun," Estrada said as he teammates roared in the background while watching Washington post a six-run inning. "That's the great thing about our team. We have a real fun group and I think that's helped us this season. Even when it looked like we were out of it, we never gave up. We just kept playing."
Axford worked around Andrew McCutchen's leadoff home run in the ninth inning, his 29th, for his 30th save in 38 opportunities. The homer broke a string of 22 scoreless innings for the Pittsburgh bullpen.
Milwaukee has won four straight games, seven of eight and 22 of 28. They are 2 1/2 games behind St. Louis in the race for the second NL wild card.
In other games: *
At Washington, Matt Kemp scored a phantom run early, then hit a go-ahead homer in the ninth inning - right after the Nats rallied with a six-run eighth - and the struggling Los Angeles Dodgers grabbed a 7-6 victory for a doubleheader split that prevented the Nationals from sewing up a playoff berth.
Kemp was credited with crossing home to give Los Angeles a 6-0 lead in the fourth, even though TV replays showed the inning's last out already had been recorded on third baseman Ryan Zimmerman's head-over-heels, reaching tag of runner Adrian Gonzalez.
That extra run loomed large when the hosts - who had won the day's opener 3-1 thanks largely to Jordan Zimmermann's six innings of one-run baseball - wound up sending 12 batters to the plate to score six runs and make it 6-all.
In the first game, the Nationals scratched out a 3-1 victory, supporting Jordan Zimmermann's six innings of one-run pitching with two RBI groundouts and a sac fly. Zimmermann (11-8) allowed six hits, walked four and hit a batter, but Hanley Ramirez's RBI single in the third produced the Dodgers' only run.
* At Miami, Kris Medlen pitched eight innings of four-hit ball and the Atlanta Braves won his start for the 21st straight time, beating the Marlins, 3-0. Medlen (9-1) struck out six, walked one and lowered his ERA from 1.62 to 1.51.
* At St. Louis, David Freese hit a two-run homer and Yadier Molina added a solo shot as the Cardinals blanked the Houston Astros, 5-0.