Already assured of a series victory against the Chicago White Sox, the host Chicago Cubs will try for a sweep of their crosstown rivals on Wednesday afternoon.

The Cubs, who hold the top National League wild-card spot, have defeated the American League Central-leading White Sox in their final at-bat in the first two games of the series.

Alex Bregman provided the heroics Tuesday, delivering a game-ending RBI single with two outs in the ninth inning to cap a 4-3 victory. The teams waited through a 1-hour, 28-minute rain delay in the bottom of the eighth.

Bregman, who is 5-for-9 in the series, also delivered a game-tying single in the seventh.

"When he gets a pitch to hit, he's doing something with it," Cubs manager Craig Counsell said. "I think that's probably the biggest thing."

The Cubs can clinch the season series against the White Sox with a victory. Four of the teams' first five meetings have been tied in the seventh inning or later.

Colson Montgomery (three hits) and Tristan Peters (two) helped keep the White Sox afloat on Tuesday.

Cubs center fielder Pete Crow-Armstrong has smacked leadoff home runs in both games and has three long balls in the series.

On Wednesday, right-hander Clay Holmes will aim for his second victory in three starts since joining the Cubs in an Aug. 3 trade with the New York Mets.

Holmes (5-5, 2.56 ERA) is 1-1 with a 3.38 ERA in two starts with the Cubs covering 10 2/3 innings. He is coming off Friday's home win against the St. Louis Cardinals, when he took a perfect game into the sixth before scattering one hit, one walk and three strikeouts in 6 2/3 scoreless innings.

Six days earlier, Holmes' club debut in Kansas City marked his first major league outing since May 15, when he sustained a fractured right fibula on a comebacker in a start against the New York Yankees.

"Step by step, I'll eventually get back to the pitcher I know I can be," Holmes said. "Obviously, I feel good and I feel like the stuff's there, but it's just getting that final little bit back is the hardest part. It's a process and I'll keep working."

Holmes is 0-0 with a 0.71 ERA in eight career appearances against the White Sox, including one start, with nine strikeouts in 12 2/3 innings.

The White Sox are expected to use Jose Urquidy as a bulk reliever. Acquired in a July 26 trade with the Pittsburgh Pirates, who previously had designated him for assignment, Urquidy tuned up at Triple-A Charlotte before making his team debut Friday.

Urquidy (1-1, 8.10) earned the victory with 3 2/3 innings of three-run, five-hit relief against the Detroit Tigers in that team debut. He matched a season high with three strikeouts while issuing zero walks for the fourth time in his last five outings.

"I was waiting for this chance for a long time," Urquidy said. "I'm here right now and enjoying it with this team."

Urquidy is 0-1 with a 27.00 ERA versus the Cubs, against whom he made his lone career appearance on April 12 at Wrigley Field. Urquidy allowed one run and three hits in one-third of an inning with one walk and zero strikeouts.