The Padres will be looking to split the series in a game matching rookie right-handers Eric Lauer (3-4, 5.47 ERA) of the Padres against Dereck Rodriguez (2-1, 4.56) of the Giants.
Lauer has pitched well in his last two starts, allowing three runs in 11 2/3 innings, but he has failed to pitch into the seventh inning in either, which could become an issue Sunday.
The Padres were forced to turn Saturday's 5-3 loss to the Giants into a bullpen affair after scheduled starter Jordan Lyles experienced tightness in his right forearm during warmups.
Five regular members of the bullpen, including emergency starter Matt Strahm, combined to throw 133 pitches, one day after Padres manager Andy Green used five relievers, including two of the same guys, to secure a 6-2 victory.
Green admitted the rotating-relievers thing, which included using three in the same inning Friday night for the first time this season, has been a bit dizzying.
"It's more a matchup thing," he explained of his three trips to the mound in the same inning. "It didn't necessarily work. We ended up giving up a run. I liked the way it played up to that point."
By allowing three, two and five runs in the first three games of the series, the Padres extended their streak of allowing five or fewer runs on the road to 13 consecutive games.
Lauer worked five innings in an earlier start against the Giants this season, allowing three runs. He did not get a decision in a game in which Green went to the bullpen four times.
It was his only previous matchup with the Giants.
San Francisco relievers have allowing five runs and six hits in 6 1/3 innings in the last two games, and have proved especially vulnerable in the ninth inning, giving up three insurance runs that padded San Diego's 6-2 victory Friday, and letting the Padres back in the game with two runs in Saturday's 5-3 outcome.
The Giants are playing the series -- and at least the next month -- without closer Hunter Strickland, who broke a finger on his pitching hand earlier in the week.
Rodriguez will try to give the Giants' bullpen a break in the series finale. But like Lauer, he has failed to give his club depth in his starts this season, averaging 4 2/3 innings in his five outings.
He has posted a win and a no-decision in his last two starts despite allowing five runs and 14 hits in 11 2/3 innings. Rodriguez has never faced the Padres.