"It was one of those you really didn't feel off the bat," said Bruce, of his 456-foot, two-run blast in the sixth inning of a 5-4 victory over the Chicago Cubs in the opener of a three-game series Monday night at Great American Ball Park.
Ryan Mattheus (1-1) earned the victory with one scoreless inning of relief.
With two outs in the sixth, Bruce crushed a 1-1 pitch from right-hander Justin Grimm (1-3) to right field for a two-run shot, putting the Reds ahead to stay.
Grimm was equally perturbed by walking Frazier prior to Bruce's homer.
"I was just trying to attack Frazier. It didn't work out," Grimm said. "I showed Bruce inside with the first pitch. I should've stayed with my strength, but I made a scouting report pitch instead. I'll learn from my mistake."
Coming into Monday's game, Cubs pitchers owned a major-league-best 2.12 ERA in July, but Richard allowed three earned runs and four hits in 5 2/3 innings.
Chicago starters had gone 12 games without allowing a home run, the longest streak by Cubs' starter since they went 13 straight game in 1988.
The top of the seventh ended in spectacular fashion when Reds second baseman Brandon Phillips fielded Jorge Soler's grounder up the middle and flipped behind his back to shortstop Eugenio Suarez, who bare-handed it for the out.
"That's the only way that play can be made to get the out," said Reds manager Bryan Price. "Our guys take a lot of pride in their defense."
Chicago had the tying run at third base with one out in the eighth but left him stranded.
Reds closer Aroldis Chapman, who threw a career-high 44 pitches Sunday in an 11-inning loss to Cleveland, pitched a perfect ninth Monday and notched his 19th save.
Chapman has recorded 54 consecutive save opportunities at Great American Ball Park.
"He's from another planet," said Bruce of Chapman.
Chicago (49-42) elevated Reds rookie right-hander Michael Lorenzen's pitch count early, and he never fully recovered, tossing 106 pitches while giving up four runs on seven hits and three walks in five innings.
"He had a long second inning," said Price of Lorenzen, who finished one pitch shy of his career-high. "They took advantage of it."
First baseman Anthony Rizzo's sacrifice fly put the Cubs ahead 1-0 in the first inning.
In the bottom of the first, Frazier, who was 0-for-10 since the All-Star break, crushed the first pitch he saw from Richard into the grassy area in center field, tying the score 1-1.
Frazier had gone 15 appearances without a homer, his longest drought of the season.
"I got out of my element a little bit," said Frazier. "I was swinging at bad pitches. It's a new week."
Richard's wild pitch in the fourth allowed first baseman Joey Votto to score from third to put Cincinnati ahead 2-1.
Byrd immediately followed with his 16th home run on a 2-0 pitch from Richard, making the score 3-1.
"They can do some damage," said Maddon. "Bruce finding his stroke makes them entirely different."
The Cubs scored three times off Lorenzen in the fifth, the key hit being Soler's two-out, two-run double that put Chicago ahead 4-3.
It could have been an even bigger inning had center fielder Dexter Fowler not been thrown out at second trying for a double.
"We made a couple of mistakes, but it was a great game," said Cubs manager Joe Maddon. "The guys kept fighting back. We just didn't win. "If you weren't entertained by that game, you don't like baseball."
NOTES: Cubs C David Ross was ejected in the seventh inning for arguing from the dugout. ... The Cubs recalled RHP Rafael Soriano from Triple-A Iowa and designated for assignment RHP Edwin Jackson. Soriano threw a scoreless inning Monday. ... Cincinnati placed LHP Manny Parra on the 15-day disabled list and recalled RHP Dylan Axelrod from Triple-A Louisville. The Reds also transferred C Devin Mesoraco to the 60-day DL. ... Both clubs announced their starters for Wednesday's doubleheader, which makes up a rainout from April 25: RHP Kyle Hendricks will pitch Game 1 for the Cubs, and RHP Dallas Beeler will be recalled from Triple-A Iowa to pitch in Game 2. Cincinnati will start RHP Mike Leake in Game 1 and recall LHP Tony Cingrani from Triple-A Louisville for the second game.