The Reds look to match their longest win streak of the season and beat their NL Central rivals for the 17th time in 19 games Sunday at Great American Ball Park.
Behind a four-run sixth and Homer Bailey's six solid innings, Cincinnati (31-18) won its fifth straight with a 5-2 victory over sinking Chicago (18-30) on Saturday.
The Reds have won 12 of 14 for their best start since winning the Central in 1995.
"This team has some big boys, veterans out on the field, and their pitching is some of the best in baseball,'' Cubs manager Dale Sveum said of the Reds. "It's tough to score on them. We're in all the games, but you can't add on or score on their bullpen.''
With Johnny Cueto (2-0, 3.22 ERA) taking the ball in the series finale, Cincinnati appears to have a good chance to win its seventh in a row versus Chicago.
The right-hander, who had missed a little over a month because of a strained muscle in his upper back, overcame a season-high four walks and allowed three runs over five innings to beat the New York Mets 4-3 on Monday.
He fanned eight, including six of the last seven batters he faced.
"I told myself I have to start pitching the way I am," said Cueto of his strong finish. "Then after that, I said, `That is me.'''
Cueto has had his own run of success against the Cubs, winning four straight starts and going 6-1 with a 1.75 ERA over his last 10 outings.
This time, he faces a Chicago team that has managed just 15 runs and a .200 batting average with runners in scoring position during its season-worst six-game losing streak.
Anthony Rizzo ended an 0-for-22 stretch by going 3 for 3 with two doubles Saturday, but he's 1 for 9 lifetime against Cueto.
Starlin Castro, who is 4 for 30 over his last seven contests, has also struggled with six hits in 27 at-bats in this matchup.
Chicago counters with right-hander Matt Garza (0-0, 0.00), who pitched well in his season debut following a 10-month layoff.
After being sidelined since July 21 because of a stress reaction in his right elbow and, later, a strained upper back, Garza struck out five and allowed one hit over five shutout innings before Pittsburgh rallied late for a 5-4 win Tuesday.
"He was really good,'' Sveum said. "He had a really good slider. His command, for it being his first time back, was outstanding. Even when he missed, he didn't miss by much. His velocity was good, too, consistently at 93-94."
Garza is 1-2 with a 3.80 ERA in four career starts against the Reds, though he hasn't faced them since 2011. He's allowed four earned runs over 10 innings in two Chicago losses at Great American Ball Park.
Shin-Soo Choo may have a tough time breaking out of his 1-for-19 funk since he's 1 for 8 with four strikeouts all-time against Garza.
Ryan Hanigan went 2 for 4 with an RBI double Saturday, raising his average to .381 with two doubles and nine RBIs in his last six games against the Cubs.