San Diego Padres (30-50) at Arizona Diamondbacks (39-39), 9:40 p.m.

Probable Starting Pitchers: San Diego - Clayton Richard (5-8, 3.77) Arizona - Trevor Cahill (6-6, 3.67)

(Sports Network) - San Diego's Clayton Richard hopes to bounce back from a tough-luck loss his last time out as the Padres play the first of three straight games against the Arizona Diamondbacks.

Richard had a three-game winning streak halted on Wednesday in Houston despite throwing seven innings of one-run ball. He allowed only two hits and did not walk a batter, but he third-inning homer he allowed to Matt Downs was the difference in the 1-0 setback.

Despite throwing a quality start for the eighth time in his past 11 outings, the left-handed Richard fell to 5-8 with a 3.77 earned run average in 16 starts this season.

"That's pitching," manager Bud Black said on San Diego's website. "Clayton's been around long enough to know that's part of pitching. I think he can take solace in the fact that he went out and pitched a heck of a game. He's pitched four outstanding games in a row. Clayton probably is one of the guys that has as good a perspective on his outings -- on baseball -- than maybe anybody in that [clubhouse]."

Richard also pitched well when he faced the Diamondbacks on June 1, giving up a run over 6 2/3 frames. However, the offense came late and the 28-year-old did not get a decision in an eventual 7-1 win.

He is, however, 3-0 with a 4.45 ERA in five career meetings with Arizona, which sends Trevor Cahill to the mound for tonight's opener.

Cahill also had a winning streak halted last time out, but shouldered much more of the blame. After escaping with a win -- his fourth straight -- over Seattle on June 20 despite allowing six runs over six innings, the right- hander was charged with another six runs -- four earned -- on four hits and four walks over five innings of a 6-4 setback in Atlanta on Wednesday.

Cahill, 24, is 6-6 with a 3.67 ERA in 15 starts this season and that includes a six-hit shutout of the Padres on June 3, the second shutout of his career. Cahill also walked three and fanned five in the win and has allowed one run in 15 career innings versus San Diego.

The Diamondbacks stumbled to a 2-1 setback at the Brewers on Sunday in the rubber match of a three-game series as Milwaukee scored the winning run in the bottom of the ninth on a handful of Arizona defensive miscues.

With one out, pinch-runner Carlos Gomez broke for second with Arizona's Patrick Corbin on the hill and catcher Miguel Montero's throw sailed into center field. Gerardo Parra then tried to nail Gomez at third, but his one- hopper skipped past Willie Bloomquist and into the stands.

"It just didn't work out, I have no problem with that play," said Arizona manager Kirk Gibson. "There wasn't a lack of effort, but concentration."

Jason Kubel's eighth-inning homer was the sole offense for the D-Backs, who have lost four of six. Josh Collmenter scattered three hits and one run with five strikeouts in six full frames.

The Padres, meanwhile, won for the third time in four games on Sunday thanks to gem from Kip Wells. In just his second start in three years, Wells hurled seven shutout innings in a 2-0 win over the Rockies in the rubber match of a three-game series.

The 35-year-old righty earned his first victory since Sept. 20, 2009 while with the Reds over the Marlins.

"Coming back here and pitching against a team I was with before and having an opportunity to pitch well was gratifying," said Wells, who threw 15 games for Colorado in 2008, including two starts.

"At the same time, that's what I expect from myself and that's obviously why they've given me the ball."

Chris Denorfia had two hits and an RBI for the Padres.

The Diamondbacks have won four of six over the Padres and the clubs are meeting for the first time in Arizona this season.