Colorado and Arizona have been NL West rivals since 1998. In all that time, the Rockies have never swept four games against the Diamondbacks at home.
Playing their 11th four-game set at Coors Field, the Rockies have a chance to finally pull it off in Sunday's series finale, though Wade Miley stands in their way.
Miley, who is 7-1 in his career against Colorado and 3-0 at Coors, is trying to help the Diamondbacks avoid a sixth straight defeat.
The Rockies (64-91), meanwhile, are on the verge of their first six-game win streak of the season after moving two games in front of Arizona (62-93) for fourth place in the West with a 5-1 victory Saturday.
The Diamondbacks have also dropped nine straight on the road - their longest such slide since a franchise-worst 14 consecutive defeats in 2010. They should like their chances of ending those woes behind Miley (8-11, 4.17 ERA), who has a 3.44 ERA over 11 starts against the Rockies.
The left-hander went 6-0 with a 2.70 ERA in eight starts versus Colorado between 2011-13 before going 1-1 with a 5.40 ERA in three this year. He improved to 3-0 with a 3.86 ERA in three starts in Denver by allowing two runs in eight innings in a 5-3 win April 6.
Miley ended a seven-start winless stretch Monday by allowing one run in seven innings to earn a 6-2 win over San Francisco. He posted a 4.81 ERA over his previous seven outings with Arizona losing all of them.
Michael Cuddyer is 4 for 15 against Miley and was rested Saturday after he had a grand slam and a career-high seven RBIs in Friday's 15-3 rout. Cuddyer is 6 for 10 with six runs scored in this series.
Wilin Rosario was also out of Saturday's lineup but should be back. The catcher is 9 for 19 in his career against Miley and has 12 hits in 17 at-bats with two homers and nine RBIs on this homestand.
Arizona rookie Ender Inciarte is 13 for 36 during a nine-game hitting streak but his club has been awful the last two nights with runners in scoring position.
"We were 0 for 11 today, so that's 1 for 20 the last two days with runners in scoring position," manager Kirk Gibson said Saturday. "We're really struggling in that respect."
The Rockies give the ball to rookie Christian Bergman (2-4, 5.56), who is 2-2 with a 4.71 ERA in five starts since he was activated from the 60-day disabled list Aug. 24. He was tagged for six runs in five-plus innings in Monday's 11-3 loss to the Los Angeles Dodgers.
The right-hander's lone start against the Diamondbacks was a 5-2 loss Aug. 29 in which he gave up one run in 5 1-3 innings and did not factor in the decision.