SAN DIEGO -- Ian Kennedy called it a "coffee grind."

"That was not good," the Padres right-handed starter said of his five-inning performance against the Cincinnati Reds on Monday night at Petco Park.

"Luckily, I go some big outs right when I needed them. And then Justin flips the game with one swing."

Left fielder Justin Upton hit a two-run homer, and Kennedy and four relievers held Cincinnati to four hits as the Padres defeated the Reds 2-1 to end a six-game losing streak.

And, no, it wasn't pretty.

The bottom line for Kennedy (7-10) looked good. He allowed one run -- on a Jay Bruce solo homer on the first pitch of the second inning -- on two hits over five innings. However, he also issued a season-high six walks and twice had to pitch out of bases-loaded jams.

By the end of the fifth, Kennedy was done after 98 pitches. Right-handed relievers Dale Thayer, Shawn Kelley, Joaquin Benoit and Craig Kimbrel all followed with scoreless innings, and Kimbrel picked up his 32nd save.

As Kennedy said, the game turned on one swing -- Upton's 20th homer of the season in the fourth. The blast immediately followed right fielder Matt Kemp's inning-opening single, the first hit allowed by Reds rookie left-hander David Holmberg (1-1).

"That is real power," Padres manager Pat Murphy said of Upton's 417-foot drive into the sand beyond the fence in right-center. "That is thoroughbred power."

Reds manager Bryan Price after Cincinnati's fifth loss in six games, "After missing those opportunities early, their bullpen shut us down."

The Reds had Kennedy on the ropes throughout the first four innings, but they pushed across only one run, when Bruce rocketed Kennedy's first pitch of the second 406 feet into the right field seats. It was the right fielder's 18th homer of the season and the 200th of his career.

Cincinnati left the bases loaded in the second and fourth and stranded a total of seven runners in the first four innings as Kennedy struggled with his command.

Kennedy walked his first hitter in the first but got out of what had been a troublesome inning for him. In his 20 previous starts, Kennedy had a 8.10 ERA in the first inning.

After Kennedy gave up his 25th home run this season to Bruce, he walked the bases loaded in the second, getting out of that jam when shortstop Eugenio Suarez popped out to second.

In the fourth, the Reds couldn't score even though catcher Brayan Pena singled with one out and Kennedy again loaded the bases with two walks around steals by Pena and center fielder Billy Hamilton. Kennedy again retired Suarez, this time on a fly to short right, to end the threat.

"I did everything I could not to give up a big hit," Kennedy said. "Those were the times I located my pitches."

Actually, Padres manager Pat Murphy thought Kennedy threw more strikes than plate umpire Tony Randazzo called. In the bottom of the fourth, Murphy was ejected by Randazzo after a heated exchange about balls and strikes.

Minutes later, Upton homered. The blast was his 20th homer of the season and his 15th of the year at Petco Park, tying the single-season record at the Padres' downtown home. The mark was set by outfielder Will Venable in 2013.

The home run accounted for the Padres' only damage against Holmberg, who allowed six hits and three walks in 6 2/3 innings. He struck out five.

NOTES: Padres RHP Colin Rea will make his major league debut Tuesday night against the Reds. Rea, 25, had a 1.98 ERA between Double-A San Antonio and Triple-A El Paso this season. ... The Padres will have to make a 40-man roster move to add Rea, who replaces RHP Odrisamer Despaigne in the rotation. Despaigne becomes the long man in the bullpen. ... RHP Michael Lorenzen (3-7, 4.84 ERA) will start for Cincinnati on Tuesday. ... C Brayan Pena had two of Cincinnati's four hits. ... Reds 1B Joey Votto went 0-for-4 with three strikeouts.