PITTSBURGH -- It's hard to know which team has momentum going into Friday's series opener between the Pittsburgh Pirates and the Milwaukee Brewers at PNC Park.

Maybe neither.

The Brewers are coming off of a 3-1 win over St. Louis that ended a 10-game homestand, but they lost six in a row before that.

The Pirates got swept in three games by the Cubs in Chicago, ending with a 6-5 loss Wednesday, after a rousing four-game sweep of the Brewers last weekend in Milwaukee, where Pittsburgh rarely has won.

Both teams had a day off Thursday.

"We got pushed down three games in a row. We just went through Milwaukee and pushed forward four days in a row," Pirates manager Clint Hurdle said.

"You just keep showing up and keep playing. It's the beauty of the sport and the beauty of what those men out there do, are built to do and are wired to do together."

While Milwaukee (57-76) dropped far off the pace, Pittsburgh (67-64) has a realistic shot at making the playoffs despite some highly streaky play. Since the All-Star break, the Pirates are .500 at 21-21.

"Ups and downs," shortstop Jordy Mercer told mlb.com. "I wish we had the answer. I don't know. I can't pinpoint one thing. It's part of it, really."

Hurdle expects his club to be resilient.

"They keep coming. Why would you back away?" he said. "You've got a month of baseball left to play, so you've got to keep pushing it out there every day, regardless if you get pushed down."

Friday's game will be the first of 17 at home this month for the Pirates, while Milwaukee will be playing the first of 18 on the road in September.

"We expected in September to be playing teams that are in the thick of things; good teams," manager Craig Counsell said. "Going on the road doesn't get any easier for us, for sure, but we'll keep going."

Just like Pittsburgh, the Brewers expect some never-quit in their game.

"You have to keep coming," outfielder Kirk Nieuwenhuis said. "That's why I really love this group. I think we have a good group in the clubhouse. We keep each other accountable for coming to play every day."

Perhaps Milwaukee can get a lift from the return of right-hander Junior Guerra, who is expected to come off of the DL (right elbow inflammation) and start Friday.

Guerra (7-3, 2.93) was arguably the Brewers' most consistent starter before getting hurt. He is 1-0 with a 1.72 ERA in three career appearances against the Pirates.

With Guerra back, the Brewers will expand their rotation to six.

"I think initially we'll definitely use six guys, so he'll just kind of slot in," Counsell said. "There'll be six guys for sure, and then we'll kind of judge it going forward from there."

Rookie right-hander Jameson Taillon (3-3, 3.39) is expected to start Friday for Pittsburgh. Taillon will look to bounce back from a tough start Saturday against the Brewers, when he allowed five earned runs on seven hits over three innings in a game the Pirates came back to win 9-6.