They share a spring training facility in Scottsdale, Ariz., their clubhouses separated by a couple of concrete walls and about 400 feet of stadium grass. They opened spring training against each other this year and met 19 times in the regular season.
All to get to the one contest that counts, the National League wild-card game on Wednesday at Chase Field.
The Diamondbacks (93-69) and Rockies (87-75) meet for the chance to continue another NL West rivalry against division-winning Los Angeles in a best-of-five NL Division Series that begins Friday at Dodger Stadium.
The staff aces, Colorado's Jon Gray and Arizona's Zack Greinke, will meet for the first time this season in a game that features two top NL Manager of the Year candidates: the Rockies' Bud Black and the Diamondbacks' Torey Lovullo. Both are in their first year on the current job. Lovullo is in his first season as a manager.
"There are no secrets here," Black said. "They know our players. We'd like to think that we know their players and what they like to do. You know, it comes down to our side trying to halt the things that they like to do. Make our pitches in certain locations, where we feel we have to pitch certain hitters. And they feel the same thing. They know our hitters' tendencies, they know our pitchers' tendencies, and we know theirs.
"So it comes down to really execution. And if you don't (execute), you know, the hitters are going to make the pitchers pay. If pitchers make their pitches, more likely than not, hitters will be out."
Arizona won 11 of the 19 meetings this season and is on a bit of a roll, having won nine of the past 13 head-to-head matchups. The Diamondbacks outscored the Rockies 101-69 in the regular season.
Mitigating any apparent numerical advantage is the fact that Greinke and Gray have had success against the other side.
Gray (10-4, 3.67 ERA) beat the D-backs twice in three starts this year, both at Chase Field. He struck out a season-high 10 in each turn in Arizona. Gray is 2-2 with a 4.75 ERA in five career starts versus the Diamondbacks.
Greinke (17-7, 3.20 ERA) beat the Rockies in Arizona and at Coors Field this season, going 2-1 with a 3.41 ERA in five starts against Colorado. Four were quality starts, and the other was two outs short. He is 9-5 with a 3.93 ERA in 25 career games (24 starts) versus Colorado.
Call both teams prepared.
"In baseball, I think we are all adrenaline junkies," Lovullo said. "We love these moments. We live for them. We prepare for them. We know now to navigate through them. I enjoy feeling pressure. I feel like the entire clubhouse feels the exact same way."
The D-backs completed a 24-game turnaround this season, the biggest in the NL, while Colorado was a plus-12.
The Rockies led the NL with 824 runs and feature a pair of MVP candidates in center fielder Charlie Blackmon and third baseman Nolan Arenado. Blackmon set a major league record with 103 RBIs from the leadoff spot, and Arenado had his third straight 130-plus-RBI season. Each had 37 homers.
Arizona scored 12 fewer runs but finished third in the NL in team ERA (3.66), improving by nearly a run and a half after having the worst ERA in the majors (5.09) last season. The D-backs have their own MVP candidate in first baseman Paul Goldschmidt, who amassed 36 homers and 120 RBIs.
A case could be made that Arizona right fielder J.D. Martinez, who bats behind Goldschmidt, is the best trade-deadline acquisition in many years. He erupted for 29 homers and 65 RBIs in 62 games after begin acquired from the Detroit Tigers on July 18. Martinez had 16 homers in September, tying Ralph Kiner's NL record for the month.
"If I say yes, it's like I don't think I can do it," Martinez said. "If I say no, it's like I'm arrogant, cocky. It's one of those things where I go up there and expect to hit the ball hard. I just feel like right now I'm having success in being able to do what I want to do up there. I feel comfortable in the box and I'm getting the results."
Greinke is 13-1 at home, one victory short of Randy Johnson's single-season record for wins at Chase Field, and he always has given his team a chance to win in the postseason. Greinke is 3-3 with a 3.55 ERA in nine postseason starts and has been better than that of late, making six starting quality starts for the Dodgers from 2013-15. Although he was only 2-2 in those six, his ERA was 2.38 and he had 41 strikeouts in 41 2/3 innings.
Gray, whose fastball was clocked at 98 mph in the sixth inning of his victory at Arizona on Sept. 12, is making his first postseason start in the Rockies' first playoff appearance since 2009. He was 5-3 with a 4.06 ERA on the road this season.
There have been three previous intradivisonal wild-card games since the current playoff format was adopted in 2012. The team with the better regular-season record won all three: the Pittsburgh Pirates over the Cincinnati Reds in 2013, the Chicago Cubs over Pittsburgh in 2015, and the Toronto Blue Jays over the Baltimore Orioles last year.