CHICAGO -- Johnny Cueto's season just keeps getting better.
Cueto (15-6) moved into a tie with New York's R.A. Dickey for the NL lead in victories. He retired the Cubs in order in four of the first five innings.
"I was feeling really good with all my pitches," Cueto said. "I was locating my pitches really well."
Back in the lineup after sitting for two games because of a recent slump, Bruce hit a two-run shot into the right-field bleachers in the fifth off Brooks Raley (0-2). Ludwick connected with a drive to left in the sixth.
Aroldis Chapman earned the save for the third game in a row, his 28th of the season. Chapman has converted 20 straight saves and hasn't allowed a run in 21 2/3 innings since blowing a save on June 24.
"He's got a good work ethic," Reds manager Dusty Baker said. "He wants it and he concentrates. He has a heck of an idea what he's doing and he's as tough as anybody I've ever had on my team."
The Reds have won three straight after snapping a season-worst five-game losing streak on Friday. Cincinnati's 22-8 record since the All-Star break is best in the majors.
In his second big league start in place of injured right-hander Matt Garza, Raley retired the first 13 Reds. He allowed five hits and three runs over six innings after giving up eight hits and seven runs in his first outing at San Diego.
Chicago has lost 10 of 11, with seven of those losses by two or fewer runs. The Cubs have been shut out four times since July 31.
Cueto, a leading NL Cy Young candidate, has allowed three runs or fewer in 20 of 24 starts and lowered his ERA to 2.45.
The Cubs put runners on the corners with one out in the sixth, the only time they had a runner reach third base. Cueto escaped the threat by getting Anthony Rizzo on an inning-ending double play.
"He was in trouble quite a few times, but got a couple key double plays," Baker said. "Johnny got behind quite a bit but he managed to get back into the count which is the sign of a good pitcher that you can get out of trouble. That was a nice shutout for Johnny."
Raley matched Cueto in the early innings, not allowing a baserunner until Todd Frazier singled with one out in the fifth. Bruce followed with his team-high 22nd homer of the season.
"(Raley) had a no-hitter, perfect game and Frazier got a big hit to put him in the stretch for the first time in the game ... and then Jay got us on the board," said Baker. "That was all the offense we needed with Johnny pitching the way he was."
"Frazier I thought hit a good pitch," Raley said. "You make a 2-0 mistake to Bruce, he makes you pay. That's part of the game. Obviously I'm still learning, got a lot to learn."
Frazier, who singled twice and scored, went 9 for 15 with six RBIs in the four-game series.
Bruce entered the game 0 for his last 12 with seven strikeouts. He sat out games on Friday and Saturday after Baker said his funk was "like being in quicksand."
Ludwick drove in his 20th run in his last 15 games, including six in the four-game set against Chicago. Since teammate Joey Votto was injured on July 15, Ludwick is hitting .341 with eight homers and 27 RBIs in 25 games.
Veteran Luis Valbuena started at third base for the Cubs for the second straight day. Manager Dale Sveum said that recent callup Josh Vitters would begin seeing more playing time at 3B, perhaps starting all three games in Chicago's upcoming series against Houston. ... Cincinnati CF Drew Stubbs struck out three times for the second straight day. Stubbs has whiffed three or more times 11 times this season. ... Cincinnati improved to 19-8 since 2010 NL MVP Votto injured his knee, increasing its lead in the NL Central from one game to 4½ over the Pirates. ... Cubs rookie Brett Jackson singled for the first hit off Cueto, breaking an 0 for 13 skid.