Mendoza was scratched from his scheduled start on Wednesday night against the White Sox after he came down with a case of strep throat. But Mendoza came to the ballpark on Wednesday, threw a light side session and felt fine.
"He went out and played catch. We wanted to keep his arm going, but we sent him back home to conserve his energy," Yost said.
Odorizzi, 22, was obtained from Milwaukee in the winter of 2010 in the trade that sent Zack Greinke to the Brewers. All four players obtained in that trade are now on the Royals' roster -- shortstop Alcides Escobar, center fielder Lorenzo Cain and pitchers Jeremy Jeffress and Odorizzi. Cain, however, is out with a leg injury.
Triple-A Omaha manager Mike Jirschele, who watched Odorizzi compile an 11-3 record with a 2.93 ERA this season, compared him with Greinke.
"He reminds me a lot of when I saw Greinke pitch at that level," Jirschele said. "Greinke might have been a little bit ahead of him with the command, but seeing both those guys pitch, they were a lot alike."
MLB.com ranks Odorizzi as the Royals' No. 3 prospect, behind outfielders Wil Myers and Bubba Starling, and ranks him 30th in all of baseball.
Yost hasn't seen Odorizzi pitch since Spring Training, so he'll be watching closely along with Royals fans. But the manager cautioned against expecting too much.
"It's his first Major League start. You let him throw it and see what it is. You can't put too much expectation on it," Yost said.
If it goes well enough, Yost likely will work with a six-man rotation for the remainder of the season and Odorizzi would face the Indians the following weekend in Cleveland. Yost won't use him in any of the seven remaining games against Detroit because the Tigers are in contention.
With a makeup game from a rainout now scheduled on Monday night at Detroit, the Royals have no more off-days before the season ends on Oct. 3.
"We'll see what happens. We'd go to six [starters]," Yost said. "With that last off-day now being a game day, there's no break from here on out. So it would be like having a break -- if we decide to go that route. We haven't decided yet, but that's what I would do if we go that route. I'm not shutting anybody down."