By MATT BEARDMORE
(AP) -- Trevor Cahill wasn't at his best in his NL debut, but the San Diego Padres weren't able to take advantage.
The Arizona Diamondbacks right-hander has not been as fortunate lately.
Cahill will go for his first victory in six starts Sunday when the Diamondbacks and major league-worst Padres close out their series at Petco Park.
Acquired from Oakland during the offseason, Cahill made his Diamondbacks debut in San Diego - about 40 miles from where he grew up - and walked six but allowed just one run in six innings of a 4-2, 11-inning victory April 10.
Since posting a 1-0 record with a 1.35 ERA in his first two starts, Cahill has gone 1-5 with a 4.69 ERA in his last eight.
Getting off to a better start could help Cahill (2-5, 3.96 ERA) get back into the win column, as he's yielded eight first-inning runs in his last five starts.
"I usually feel good in the first inning," he said after giving up three runs in the first frame of Monday's 4-2 loss at San Francisco. "For some reason this year, maybe coincidence, it's taking me more time to feel comfortable."
Cahill will face a San Diego team that's dropped 10 of 12, including Saturday's 4-2 loss.
The Padres (18-36), who ended a season-high six-game skid Friday with a 7-1 victory, try to get back on track with Eric Stults (1-1, 3.00) on the hill.
The left-hander, who was claimed off waivers May 17, will make his fourth start with San Diego after giving up four runs in 6 1-3 innings of Tuesday's 5-3 road loss to the Chicago Cubs. Stults was hit on the arm by a line drive in his previous start May 24 against the New York Mets.
"I didn't feel it at all," he said. "The only thing I can feel now, coming out of the game, is it's stiffened up, but that's to be expected."
Stults last faced Arizona (24-29) on July 23 when he allowed four runs in 2 1-3 innings out of the bullpen for Colorado. It was his last major league appearance of the 2011 season; he was designated for assignment two days later.
Stults, though, has a 2.45 ERA while winning both of his starts against the Diamondbacks - both in 2009 while with the Los Angeles Dodgers.
He should be careful pitching to first baseman Paul Goldschmidt, who had a solo homer Saturday to extend his career-best hitting streak to 11. He's batting .400 with three homers during that run.
Shortstop Willie Bloomquist is hitting .409 (9 for 22) in five games against San Diego this season following Saturday's 3-for-5 effort.
Diamondbacks right fielder Justin Upton, 1 for 10 against Padres pitching this season, should be back in the lineup Sunday after getting Saturday off.
Even though left fielder Carlos Quentin is hitting .474 (9 for 19) with three homers and seven RBIs since coming off the disabled list earlier this week, Padres manager Bud Black could give the former Diamondback a break Sunday in favor of Jesus Guzman, who had a pinch-hit two-run homer Friday.
Arizona has won four of six at San Diego.
Updated June 3, 2012