The Padres will seek their 10th win in 12 home games and their fourth in a row overall in Wednesday night's series finale against the Cubs, losers of seven straight.
Chicago (43-65) is 0-12 when visiting NL West opponents this season, including an 0-9 mark in California. The Cubs have been outscored 38-16 while batting .170 during their current seven-game overall skid.
They trailed by seven runs after four innings Tuesday, en route to a 7-4 defeat.
The Padres (48-64) have posted a 2.65 ERA over their last 11 home games, outscoring the opposition 56-35. They have a chance for their first three-game home sweep of the Cubs since May 22-24, 2009.
Clayton Richard (8-11, 4.01 ERA) will try to help his team pull off that feat. The left-hander is coming off one of his better starts of the season. He gave up one run and scattered eight hits over seven innings of Friday's 3-1 win over the New York Mets.
"It's a great sign. We've seen him better and he goes seven-plus and gives up one run," manager Bud Black told the Padres' official website. "That's where he is right now in his game: We expect those type of outings from Clayton."
Richard won his only career start against the Cubs on Aug. 18, 2010, allowing one run over 6 2-3 innings. In this matchup, he'll pitch opposite Jeff Samardzija (7-9, 4.37), who will try to bounce back from a difficult outing.
The Chicago right-hander gave up five runs over 5 1-3 innings of a 6-1 loss to the Los Angeles Dodgers on Friday, a significant setback after going 2-1 with a 1.91 ERA over his previous five starts.
"I've got to keep the ball down in the zone and get some clutch outs when I need them to keep the team in the game," he said. "Every start that I make is important. So I need to pitch deeper into games and be efficient."
Samardzija won his only start against the Padres on May 29, allowing three runs over seven innings and striking out eight.
It's unknown if Alfonso Soriano will be able to help him. The Cubs slugger was scratched from Tuesday's game with a sore right hand, which he suffered after he was accidentally spiked while sliding into second base Monday.
Padres outfielder Carlos Quentin is 9 for 18 with four homers and nine RBIs in five games against the Cubs this season. He hit a three-run shot in Tuesday's win, and went 3 for 3 with a home run and a double off Samardzija in May.