KANSAS CITY, Mo. -- With Danny Duffy and Ian Kennedy on the disabled list, the Kansas City Royals' rotation consists of four freshmen -- Glenn Sparkman, Jorge Lopez, Brad Keller and Heath Fillmyer -- and one sophomore in Jakob Junis.

Sparkman will make his first career start on Thursday night against the Toronto Blue Jays after eight relief appearances. Lopez, who was acquired from the Milwaukee Brewers as part of the Mike Moustakas trade, made his third career start on Wednesday.

Junis has made 38 starts, including 16 as a rookie last year. Keller has made 13 starts and Fillmyer six.

Sparkman (0-1, 5.06 ERA) is the oldest of the quintet at 26, while Lopez and Junis are 25. Fillmyer is 24 and Keller just turned 23.

"It's just getting your feet wet and understanding how good you can be," Royals manager Ned Yost said. "It's about commanding the strike zone and changing speeds. It's not pitching behind in the count with good stuff. It's about pitching ahead in the count with good stuff.

"It's just continuing to trust in your stuff, believing in your stuff and go out and compete within yourself."

Fillmyer walked five -- three wound up scoring -- and hit a batter in five innings in a no-decision Tuesday against the Blue Jays. While Keller won on Monday, Yost mentioned he threw more balls than strikes in the first two innings.

"That's not going to work," Yost said. "You have to get ahead in the count. Instead of five-six pitch decisions, there were three-and-four pitch decisions (after the second inning). He was ahead in the count. He did a better job of keeping them off-balance. You always can when you're ahead in the count.

"You're behind in the count, they are sitting on your best percentage pitch. Most of these guys, it's a fastball. When you're ahead in the count, they can't do that. It creates a little bit of a doubt. Their stuff is all good enough to be successful when that little bit of doubt is in the back of a hitter's mind."

Sparkman threw 68 pitches over 4 1/3 innings in a relief appearance Friday against St. Louis. He retired 12 of the first 14 batters he faced before giving up a home run to Harrison Bader in the sixth.

"These young guys they think they're good now, but until you know you're good, it's a big door to walk through: thinking you're good and knowing you're good. Once you know you're good, you've got it. These kids for the most part, their stuff is pretty good. They'll continue to refine and develop their pitches and their command."

Toronto will counter with right-hander Sam Gaviglio, who was 1-0 with a 3.00 ERA in four outings, including two starts, last September with Kansas City. The Royals traded him to the Jays in spring training for a player to be named.

Gaviglio (2-5, 4.86) said facing his former team for the first time does not give him an extra incentive.

"They gave me a chance last year," Gaviglio said. "I'm thankful for that. I'm still friends with a lot of guys. I got to catch up with them a little bit a couple of days ago.

"I don't think it really changes anything. As long as I execute my pitches, I'll be fine."

Gaviglio has struck out 14 in 11 innings in his past two starts.

"I think a little more consistency," Gaviglio said. "I think everything's kind of coming out a lot more off my fastball than it has in the past. Just learning myself and how to execute and what I want to do to hitters."

In his last eight starts, he has pitched through the sixth inning only once.

"Just attack guys and get some early outs, some quick outs," Gaviglio said of his goal to pitch deeper into the game. "We've got some good catchers here and defense. Just trust it."

The Blue Jays are 5-1 against the Royals this season after winning 6-5 Wednesday night behind Curtis Granderson's two-out, fourth-inning grand slam. Lopez was the losing pitcher in his Kansas City debut.

Toronto is 12-13 since the All-Star break. The Royals have lost 11 of their last 13 and dropped to 36-84 for the season.