Jorge De La Rosa will take the mound for the Rockies for the 15th time this season, though just the sixth away from Coors Field. He has been dominant in his five road starts this season, with a 1.67 ERA in 32⅓ innings, walking 13 and striking out 26.
First baseman Yonder Alonso is the only lefty in the Padres lineup against the southpaw De La Rosa, with regular shortstop Alexi Amarista on the bench. Taking Amarista's place at shortstop is Will Middlebrooks, who will be making his fourth career professional start there.
James Shields will take the mound for the Padres for his third start against the Rockies this season. The Padres' ace struggled in his first two starts against Colorado, allowing eight runs in 11⅓ innings, a 6.35 ERA.
The Rockies have most of their regular starters in the lineup, with the exception of Michael McKenry behind the plate and Drew Stubbs in left field. Carlos Gonzalez also moves up to the second spot in the order for the first time since May 14.
First pitch at Petco Park is at 8:10 p.m. Mountain time.