Edinson Volquez hopes to remain undefeated against Chicago and help the Padres to a fifth straight home victory over the lowly Cubs on Friday night.
San Diego (57-70) is 34-31 at Petco Park, but has dropped six of nine there. Though the Padres won 2-1 over Pittsburgh there Wednesday, they totaled four runs while losing two of three in the set.
Chicago (54-73) has four more wins on the road than at home in 2013, but has been outscored 20-6 during a four-game slide at Petco.
Losers in three straight, the Cubs have averaged 3.4 runs while losing 18 of 24 overall.
"We're out there fighting and battling," Chicago starter Edwin Jackson told the Cubs' official website. "Sometimes things don't work in our favor, sometimes things don't look the best the way we do them.
"Everybody is giving 110 percent, and at the end of the day, that's all you can ask for."
Though Volquez (9-10, 5.72 ERA) gave up four runs on two homers and walked three in 5 2-3 innings April 30 at Wrigley Field, he improved to 5-0 with a 2.76 ERA in seven starts against the Cubs.
The right-hander, 1-1 with a 3.12 ERA in his last three home starts overall, allowed two runs and seven hits in an 8-2 win over the New York Mets on Saturday but lasted only five innings.
"That wasn't the most efficient outing," manager Bud Black told the Padres' official website, "But the end result is giving up two runs."
Jackson (7-13, 4.89), who was roughed up for eight runs and 11 hits in 4 2-3 innings of that April loss to Volquez, is 0-4 with a 5.56 ERA in seven starts versus San Diego.
The right-hander has allowed 11 runs in 10 innings to go 0-1 in his last two road starts, and also lost Sunday when he allowed three runs - one earned - with four walks in six innings of a 6-1 defeat at home to St. Louis.
San Diego's Yander Alonso is 5 for 9 with two doubles and a homer against Jackson.
He had two hits and drove in both runs Wednesday after going 0 for 8 in the first two games of the series.
"I'm in the middle of the lineup. You'd expect me to do those things," Alonso said.
Teammate Will Venable is batting .353 with 12 RBIs in his last 31 games, but went 0 for 6 when the Padres split a four-game set at Wrigley this season.
He's 1 for 9 with a homer versus Jackson.
Chicago's Donnie Murphy is 1 for 7 versus San Diego, but 7 for 18 with four home runs and six RBIs in the last four games. He hit a tying, two-run homer in the ninth of Thursday's 5-4, 13-inning loss to Washington.
The 30-year-old journeyman has a career-high eight homers and 15 RBIs in 16 games for the Cubs.