Pittsburgh will start Ian Snell who went 2-0 in his first three starts this season, but hasn't won since allowing three runs in 6 1-3 innings of a 4-3 victory over the Reds on April 12.
The right-hander gave up four runs - two earned - with nine hits and six strikeouts in six innings of a 4-1 loss to Milwaukee on Wednesday.
The Reds will counter with Johnny Cueto (2-5, 5.56), who has one win in his last nine starts.
The 22-year-old rookie right-hander allowed four runs - two earned - and seven hits in five innings, while throwing a career-high 114 pitches in a 5-2 loss to the Los Angeles Dodgers on Wednesday.
Cueto suffered his first career loss in his only start against the Pirates on April 13, giving up five runs in six innings of a 9-1 defeat.
The Jay Bruce era begins Tuesday in Cincinnati.
The club announced Monday it will call up the 21-year-old outfielder who was its No. 1 draft pick in 2005 in time for Tuesday's game against the Pirates.
While the club believes Bruce is best suited at a corner outfield spot, he could play center this year, then move to a corner spot when the team decides what it is going to do with Ken Griffey Jr., who is in the last year of his contract, and/or Adam Dunn, who can become a free agent after this season.
Bruce was named last year's Minor League Player of the Year by both Baseball American and The Sporting News.
Many believe he should have made the team out of spring training, but outfielder Corey Patterson instead was signed midway through spring training and is hitting .201 with a .242 on-base average.
Meanwhile, Bruce annihilated Class AAA pitchers at Louisville this year, hitting .364 in 49 games with 10 home runs, nine doubles, five triples, 37 RBIs and eight stolen bases.
He leads the International League in hitting and hits (67) and is among the league leaders in slugging percentage (third at .630), runs scored (fourth with 34), extra-base hits (fourth with 24) and RBIs (fifth).
--CF Corey Patterson went 0-for-8 in an 18-inning loss to the Padres Sunday, the first Reds player to go 0-for-8 since CF Eddie Milner was 0-for-8 in a 1983 game at San Francisco.
--RHP Aaron Harang struck out nine in a four-inning relief job Sunday, matching his season high in strikeouts over 11 starts.
--C Paul Bako is 0-for-19, one hitless at-bat shy of his career worst, 0-for-20 Aug. 7-27, 2002.
--RHP Johnny Cueto (2-5, 5.56) makes his 11th start Tuesday, the first time he has faced a team twice after losing to the Pirates April 13, giving up five runs and five hits in six innings of a 9-1 loss.
QUOTE TO NOTE: "I don't want to try to explain it or analyze it; I just want to keep doing it to help my team win." -- 1B Joey Votto, talking about his 10 homers when his minor league statistics gave no indication of heavy firepower.