The surging Kansas City Royals own baseball's best interleague record at 14-4.
Their final two such contests are against the NL's worst team.
Kansas City (69-55) holds a two-game AL Central lead over Detroit and is a major league-best 16-3 since July 30 as it searches for its eighth straight interleague road win. Colorado (49-75) owns baseball's worst record since that date at 6-12.
The Royals used strong starts from James Shields (11-6, 3.29 ERA) and Jason Vargas to take two home games May 13-14 from Colorado. Shields also starts the opener of this two-game set.
Matzek (2-8, 5.50) had not reached the big leagues at that point, getting recalled from Triple-A Colorado Springs on June 11 and remaining in the rotation since.
No NL rookie has more losses than Matzek, who has a 9.60 ERA in dropping all three starts this month. He struck out a season-high nine while giving up five runs over six innings in Wednesday's 5-3 loss at San Diego.
The left-hander is 0-2 with a 10.80 ERA in two interleague starts.
Shields is 3-0 with a 2.55 ERA in five contests against the NL. He limited the Rockies to one run and struck out eight in seven innings in a 5-1 win May 13.
The right-hander's only other start against Colorado was his lone one at Coors Field in 2007. None of the Rockies he faced in that game are currently available.
Shields has plenty of experience against Justin Morneau (15 for 44 against him with four homers) and Michael Cuddyer (7 for 17). He hasn't allowed more than three earned runs in his last eight starts, going 3-2 with a 1.94 ERA.
Morneau is day to day after he missed Sunday's action with a stiff neck.
Shields is one of five AL pitchers with two hits at the plate this year.
Kansas City captured its eighth straight series by taking three of four at Minnesota to start a nine-game trip, winning 6-4 on Monday. Alex Gordon went 8 for 15 in the series and Billy Butler, hitting .400 in his last 15 games, was 7 for 17.
Catcher Salvador Perez had two hits and two RBIs before leaving in the seventh inning. Manager Ned Yost said Perez tweaked a tendon in his knee while running the bases in the fifth, but was removed purely as a precaution.
Erik Kratz replaced Perez and hit two solo homers.
''It's great to help the team out when you do get in there for any bench guy,'' Kratz said.
The injury-plagued Rockies received a boost when Cuddyer returned after missing 60 games with a left shoulder fracture for Sunday's doubleheader sweep of Cincinnati. He went 5 for 10 and hit for the cycle in the nightcap.
''It's good to see Cuddy out there and swinging like it's midseason form,'' manager Walt Weiss said. ''Big night for Cuddy.''
Rockies outfielder Corey Dickerson was 4 for 9 with a homer and five RBIs in the two games. He is batting .417 during a career-best 12-game hitting streak but went 0 for 3 off Shields in May.