Arizona's Ian Kennedy and San Diego's Clayton Richard have both struggled with inconsistency this season.
However, that has not been the case for each when facing the other's ballclub.
Kennedy and Richard each look to continue their respective success against their opponent when the visiting Padres try to match a season high with a sixth consecutive victory Saturday night against the Diamondbacks.
Kennedy (11-10, 4.24 ERA) is 6-0 with a 2.34 ERA in nine starts versus San Diego, including 1-0 with a 3.46 ERA in two this season. The right-hander, though, wasn't at his best July 4 when he allowed four runs and nine hits in seven innings of an 8-6 home loss to the Padres.
He gave up 11 runs - eight earned - and four homers over 10 innings while losing his two previous starts overall before yielding a run and overcoming five walks in six innings of an 8-1 victory at Houston on Sunday.
"I put a lot of hitters in hitters' counts and just luckily got out of it," Kennedy told the Diamondbacks' official website.
Kennedy is 3-0 with a 3.98 ERA in his last five home starts in which he's received an average 8.53 runs of support.
Richard (10-12, 3.73) is 4-0 with a 3.89 ERA in six starts versus Arizona, including 1-0 with a 1.76 ERA in two 2012 outings. He allowed two runs in 8 2-3 innings of a 6-2 win July 2 at Chase Field, where he is 2-0 in three starts despite a 5.00 ERA.
Though the left-hander is 0-3 with a 6.00 ERA in four road starts since that victory at Arizona, he hopes to build on Sunday's effort when he gave up a run in eight innings of a 7-1 home win over San Francisco.
"He continues to go out and pound the strike zone and get ahead of guys," teammate Cameron Maybin told the Padres' official website. "He's just fearless. You love playing behind a guy like that."
Richard looks to help San Diego (57-70) continue its success after winning 5-0 at Arizona on Friday. Eric Stults threw seven strong innings and drove in a career-best three runs with a pair of two-out hits for the Padres, who have outscored the Diamondbacks 35-19 during a franchise-best five-game winning streak at Chase Field.
San Diego outfielder Chris Denorfia, who hit a solo homer and drove in two runs Friday, is batting .425 (17 for 40) in 12 games at Arizona. He's 3 for 9 against Kennedy.
Chris Young had two of the four hits for the Diamondbacks, who have dropped five of their last six series openers.
Arizona slugger Justin Upton, who was reported to have been claimed off waivers by an unidentified team this week, could miss a fourth straight game because of a nagging hamstring injury.
"We're going to give him another day," manager Kirk Gibson told the Diamondbacks' official website.
Though Upton is batting .273 with a disappointing nine homers and 49 RBIs, he is 5 for 11 with three RBIs in his last three games. He's 5 for 15 versus Richard.