With less than six weeks to go in the regular season, the various postseason races are really starting to heat up, and there may not be a more wide open race than the NL wild card. Four teams are competing for two spots at the moment.

This weekend in Denver, two of those four teams will meet for a three-game series as the Colorado Rockies host the St. Louis Cardinals for three games at Coors Field. A few weeks ago this looked like it might be a meaningless series. Instead, it is very important for both clubs, as well as the other wild-card hopefuls. Here are the tentative pitching matchups:

DateStart Time TVRockies SPCardinals SP

Friday, August 24

8:40 p.m. ET

FS Midwest/ATT SportsNet-RM

Antonio Senzatela (4-3, 4.47)

Miles Mikolas (13-3, 2.80)

Saturday, August 25

8:40 p.m. ET

FS Midwest/ATT SportsNet-RM

German Marquez (11-9, 4.42)

John Gant (5-5, 3.76)

Sunday, August 26

3:40 p.m. ET

FS Midwest/ATT SportsNet-RM

Tyler Anderson (6-6, 4.45)

Austin Gomber (3-0, 2.98)

Fans in the St. Louis market can stream the series on fuboTV (Try for free).

Neither Kyle Freeland nor Jon Gray, Colorado's two best starters, will get the ball in this series, putting the Rockies at something of a disadvantage. That said, once you adjust for ballpark, the three starters the Rockies are sending out there this weekend have all prevented runs at an above-average rate this season. The Cardinals? They've reinvented their rotation on the fly.

"The Cardinals pitching staff, they are unrecognizable. There is no Carlos Martinez in the rotation, there is no Adam Wainwright in the rotation, there is no Michael Wacha in the rotation," said Jonah Keri on CBS Sports HQ (video above). "... (The Cardinals) are really turning over a whole staff. It's remarkable the way the Cardinals have done that this season. And actually, if you want a reminder of what this looks like -- a staff sort of coming out of nowhere with almost all new guys -- that's really what the 2017 Rockies did. Other than Jon Gray, new faces everywhere, and it totally worked. That's what's happened so far for the Cardinals."

The surging Rockies and equally surging Cardinals will play three very important games with major postseason implications this weekend at Coors Field. Here's what you need to know going into the series.

The NL wild-card race is tight

Like I said, there are four teams competing for the two wild-card spots at the moment, and those four teams are in a virtual tie in the standings. Here is the NL wild-card picture coming into Friday, with SportsLine projected records and postseason odds:

TeamW-L GB Run DiffProjected W-L Postseason Odds

Cardinals

71-57 (.555)

+1/2

+63

90-72

72.7%

Rockies

70-57 (.551)

-

-8

87-75

39.6%

Brewers

71-58 (.550)

-

+27

88-74

53.0%

Phillies

69-58 (.543)

1/2

+3

86-76

31.1%

Dodgers

67-61 (.523)

3 1/2

+106

89-73

57.3%


Make sure to check out SportsLine's daily pick sheet for insight about every game
.

The Rockies are percentage points -- percentage point, really -- ahead of the Brewers for that second wild-card spot. With five weeks and three days to go in the regular season, there are four teams essentially tied for the two wild-card spots, with the Dodgers looming.

Because the race is so tight, these head-to-head series take on added importance. It's a chance for the Cardinals and Rockies to create some separation with at least one of those other wild-card hopefuls. Counting on other teams for help late in the season is no fun. Best to take care of business yourself, and this weekend is a chance for the Cardinals and Rockies to do just that. 

It should be noted that, while the Rockies are competing for a wild-card spot, they are only one game back of the Diamondbacks in the NL West. Winning the division is obviously preferable to settling for a wild-card spot and surely their goal is the NL West title. The Cardinals are three games behind the Cubs in the NL Central. 

These are two the hottest teams in the NL

Both the Cardinals and Rockies go into this weekend's series having won eight of their last 10 games, but their hot streaks extend much further back than that. St. Louis swept the Dodgers in Los Angeles earlier this week and they are 13-2 with a plus-43 run differential in their last 15 games. They are 23-11 since Mike Matheny was let go.

As for the Rockies, they took two of three from the Padres earlier this week, with Ian Desmond's two-run walk-off home run providing Thursday's win.

The Rockies are 10-2 in their last 12 games and they're 32-15 in their last 47 games now. Colorado not only has the National League's best record since June 27, they've allowed the second fewest runs in the league (181) since that date. (The Dodgers have allowed 180 runs since June 27.)

Going into the All-Star break, the Rockies were two games back of the second wild-card spot while the Cardinals were four games back. They've both climbed up the standings in the month since the Midsummer Classic.

This is not their first meeting of 2018

The Rockies and Cardinals played four games at Busch Stadium from July 30 to August 2. The Cardinals won three of four, with two of the three wins coming via walk-offs. Marcell Ozuna hit a walk-off solo home run on July 30 and Jose Martinez provided a two-run walk-off single on August 2.

That series was played during the time in which Colorado's bullpen seemed to blow a lead every night. They suffered three walk-off losses in the span of five games and the high-priced relief crew of Wade Davis, Jake McGee, and Bryan Shaw just couldn't seem to get anyone out. They've been better of late, however.

The Cardinals currently lead the season series 3-1 and that is not insignificant. The head-to-head record could come into play for postseason tiebreaker scenarios. The Rockies need to sweep this weekend to clinch the season series win and thus tiebreaker status over the Cardinals. St. Louis needs just one win to do so.

Welcome to Coors Field, Cardinals pitchers

The Cardinals' three starting pitchers for this weekend's series have combined for one (1) career inning at Coors Field. That inning belongs to Mikolas, who allowed four runs (three earned) in one inning of relief back when he was with the Padres in 2012. That was before he went to Japan and reinvented himself. Neither Gant nor Gomber have ever pitched in Colorado's hitters' haven.

Generally speaking, pitchers who get ground balls and throw a lot of fastballs have the most success in Coors Field. Keeping a ball on the ground is an obvious plus, and because breaking balls don't break the same way in the thin mountain air, the more fastballs, the better. Here's a breakdown of the three starters the Cardinals are sending to the mound this weekend:

PlayerGround Ball Rate Fastballs Breaking Balls Changeups

Miles Mikolas

50.4%

48.2%

47.5%

4.4%

John Gant

44.8%

55.3%

18.1%

26.6%

Austin Gomber

35.9%

49.6%

43.2%

7.1%

Gomber might be in for some trouble Sunday. He is not a ground ball pitcher at all -- Gomber has a 38.4 percent ground ball rate in Triple-A this year, so it's not a sample size issue, fly balls are his M.O. -- and he throws a lot of breaking balls. I'm curious to see how Mikolas handles Coors Field. He's gotten plenty of ground balls this year but he throws a lot of breaking balls. How effective will his curveball and slider be at altitude?

Holliday will face his former team

Welcome back to the big leagues, Matt Holliday. Holliday signed a minor-league contract with the Rockies earlier this year and they called him up Thursday. He went 0 for 3 as the left fielder and No. 5 hitter in his return to Colorado.

Holliday is back in the big leagues with his former team and this weekend he'll face another one of his former teams, the Cardinals. He played with the Rockies from 2004-08 and the Cardinals from 2009-16, with a short stint with the Athletics in the middle. Quite a coincidence, eh? Holliday signs with a former team and they call him just as they're about to play one of his other former teams in a rather important series.

This is Players' Weekend

It is Players' Weekend, and that means players across the league will wear special uniforms with nicknames on the back. Here are the jerseys the Rockies and Cardinals will wear this weekend:

rockies-cardinals-players-weekend.jpg
The Rockies and Cardinals will play a huge series during Players' Weekend. MLB.com/CBS Sports

While I respect the Rockies for going with purple as their primary color, I think I prefer the Cardinals' Players' Weekend jerseys. Either way, I am very much pro-Players' Weekend. Anything that spices up the dogs days of summer and allows players to show a little personality is a-okay with me.