The Kansas City Royals are ready to give Jeremy Guthrie another chance to join their postseason rotation.

He'll make his first start in just over a month Tuesday night and will face a tough opponent in Seattle Mariners starter Hisashi Iwakuma in the opener of a three-game home series.

Kansas City (87-62) can clinch a tie for the AL Central crown by winning Tuesday along with a loss by second-place Minnesota at home to Cleveland. The Royals are closing in on their first division title since 1985.

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Edinson Volquez, Yordano Ventura and Johnny Cueto are seemingly entrenched as the top three postseason starters for the Royals, though none have pitched particularly well this month. Kansas City opted to demote Danny Duffy to the bullpen after he went 0-2 with a 5.59 ERA in his last four starts.

Manager Ned Yost said the demotion was related solely toward gearing up for the postseason.

"We're getting to the end of the year, and we only need four starters for the playoffs," Yost told MLB's official website. "If this was in the middle of the season, we probably wouldn't be talking about this."

Guthrie (8-7, 5.55 ERA) is the beneficiary after he went 1-2 with a 6.48 ERA in his first six starts after the All-Star break to lose his spot in the rotation. The right-hander has posted a 4.70 ERA in five relief appearances since.

"I feel I'm a more effective asset to the team as a starter," Guthrie said. "But the team needs to win. If we were winning, there probably wouldn't be the opportunity for me again to start."

Guthrie is 2-8 with a 5.72 ERA in 14 starts against Seattle (73-77), which scored six runs in five innings against him in a 7-0 victory June 23. Nelson Cruz, vying for the major league lead with 42 homers, is 6 for 27 without going deep versus Guthrie.

The Royals are losers of 11 of 16 as they try to solve Iwakuma (8-4, 3.90), who is 2-0 with a 2.14 ERA in three career starts against them. Eric Hosmer and Ben Zobrist each have gone 4 for 9 in this matchup while Alex Rios bats .200 off Iwakuma.

The right-hander is an MLB-best 19-6 on the road over the last three years among pitchers with a minimum of 10 decisions, posting a 3.10 ERA. The Mariners have won his last six road outings, with Iwakuma going 4-0 with a 2.23 ERA with three straight wins.

He left after six innings with back tightness after he gave up one run and struck out a season-high nine in Wednesday's 3-1 home win over the Los Angeles Angels.

"It's nothing major, it's minor," Iwakuma said through an interpreter. "I've been battling this situation for a while now and it got tight."

Royals shortstop Alcides Escobar sat out the last two games with an elbow contusion, with Christian Colon replacing him.

His Mariners counterpart, Ketel Marte, is batting .375 in an eight-game hitting streak. Seattle opened a nine-game trip by taking two of three from Texas over the weekend.