San Diego, CA -- (Sports Network) - Brian Giles hit a three-run homer and Kevin Kouzmanoff drove in three runs, as the San Diego Padres spoiled Brandon Webb's bid for his 20th win with a 9-2 victory over the Arizona Diamondbacks in the continuation of a three-game series at Petco Park.

Chad Reineke (2-1) pitched five innings and allowed two runs on two hits to earn the victory for San Diego, which has won two straight on the heels of a seven-game skid. Chase Headley added a pair of RBI in the victory.

Mark Reynolds' two-run blast provided the only offense for the Diamondbacks, who have lost three straight and four of their last five games overall. Despite the setback, due to another loss by the LA Dodgers, the D'Backs still hold a three game lead atop the NL West.

Webb (19-5) suffered through an unusually poor outing in which he yielded six runs on nine hits in 4 2/3 innings. Webb's next attempt to become the National League's first 20-game winner since 2005 will commence on Sunday, when he is scheduled to take the hill at home against the Dodgers.

"It was very atypical -- you don't see that very often," said Arizona manager Bob Melvin about Webb's struggles. "From the third inning on, he looked like he did not have good stuff, and very rarely do you see that."

The Padres broke the game open with a five-run third inning. After consecutive singles by Nick Hundley and Tadahito Iguchi, Giles belted his 10th home run of the season over the wall in right field. Later in the stanza, with two runners on base, Kouzmanoff's double to deep center gave the hosts a 5-0 advantage.

"You want the ball up in the zone because (Webb's) sinker runs pretty hard away from you," said Giles. "(The count) was 3-1 and (Webb) left the ball out over the plate and I was able to handle it."

Arizona scored its only runs of the night in the top of the fourth. Adam Dunn singled and came home when Reynolds followed with his 25th homer.

In the fifth, Headley's RBI single made it 6-2.

A pair of runs for San Diego in the bottom of the seventh pushed its lead to six. With Leo Rosales on the mound, Adrian Gonzalez drew a one-out walk and came around to score on a Kouzmanoff double. The next batter was Headley, who roped a single to center field and Kouzmanoff came home.

The scoring was capped by Jody Gerut's RBI single in the eighth.

Five San Diego relievers -- Clay Hensley, Mike Adams, Brian Fallen, Heath Bell and Brett Tomko combined to pitch four scoreless innings of one-hit ball with four strikeouts and three walks.

Game Notes

The Padres outhit the D-Backs, 13-3...The last 20-game winner in the NL was Dontrelle Willis, who won 22 with Florida. He is also seeking to join Randy Johnson and Curt Schilling as the only pitchers in club history to reach the 20-win mark. The six earned runs he allowed in this one raised his earned run average from 2.74 to 2.96. Webb fell to 6-8 lifetime against the Padres in 22 starts...Reineke fanned four and issued four walks...Giles has now scored 430 runs as a Padre, which ties him with Gary Templeton for sixth place on the all-time runs scored list in club history...Attendance was 32,104.