Pittsburgh (56-52) won the opener of a two-game series between the clubs at PNC Park 5-4 Tuesday to move within six games of the Cubs (61-45) in the National League Central.
The Pirates have won three of four, and 14 out of their last 17 games. Chicago has lost three of four.
Chicago made one move Tuesday, acquiring right-hander Brandon Kintzler from Washington for a minor-leaguer. The Cubs already had made their bigger moves, acquiring left-handed starter Cole Hamels -- who is scheduled to make his Cubs debut Wednesday against Pittsburgh -- and reliever Jesse Chavez.
"We addressed what we wanted to address," Chicago general manager Jed Hoyer said.
Pittsburgh made a bigger splash in the hours leading up to the deadline, adding right-handed reliever Keone Kela from Texas and, in a trade that caused a stir on social media, starter Chris Archer from Tampa in exchange for right-hander Tyler Glasnow, rookie outfielder Austin Meadows and a player to be named.
The Pirates won 15 of 19 games leading up to the deadline, which led to the players delving heavily into their game faces and convincing management to become buyers rather than sellers.
"That's a move they wanted to make. That's a move they believe is going to push us over the edge," Pirates first baseman Josh Bell said of acquiring Archer. "We're just going to go out there every night and do what we do best, and that's play the game of baseball and continue to try to get wins.
"We really didn't know what was going to happen. We kind of forced the issue [recently] and [we're] definitely happy to continue to progress."
Pittsburgh also recalled infielder/outfielder Chris Bostick from Triple-A Indianapolis.
Rookie right-hander Nick Kingham (5-5, 4.80 ERA) is scheduled to face Hamels (5-9, 4.72 ERA with Texas) Wednesday.
Kingham, whose spot in the rotation could be tenuous with the arrival of Archer and Chad Kuhl due back from the disabled list at some point, has won three of his past four starts. The loss in that stretch was his most recent outing, when he got rocked for six runs and seven hits in three innings in a 12-6 loss Thursday against the New York Mets.
He is 0-1 with a 3.86 ERA in two career starts against the Cubs.
Hamels, a four-time All-Star who began his career with Philadelphia, has struck out 114 batters in 114 1/3 innings this season.
"This is a great division to play in," he said of the NL Central. "I was able to have great success when I was in the National League.
"With what [the Cubs] have been able to do this season, hopefully, I'll fit right in and do my thing and get them some wins."
That would mean moving past a poor July, when he was 1-3 with an 11.12 ERA in four starts.
"July was not a fun month," Hamels said. "I've known this whole year I was struggling mechanically. It was a struggle to try to get right, and fortunately, you keep going out there. I wasn't able to make the necessary corrections until recently. I've been healthy the whole time. It's just a matter of trying to be in sync and letting the results happen."
He is 3-3 with a 2.93 ERA in 10 career starts against the Pirates.