In Interleague play in National League cities, there's no DH and the pitchers hit.
"We're trying to get our best bats in the lineup. You can't have Billy sitting out," manager Ned Yost said. "We're not sitting Hoz out, he's swinging the bat much better now."
Hosmer and Francoeur have been working out at their new positions for the past three weeks and Butler is constantly practicing at first base.
"When you're a lefty in Little League and a pretty big kid, there's not many positions you can play, so I've been stuck at first base for a while and it'll be fun for me to be out there," Hosmer said.
Hosmer played the outfield briefly in two Spring Training games, but has not played there in the Minor Leagues or the Majors. He last played outfield regularly in summer ball as a high school senior. Francoeur has played center field in the Majors just twice, both times in 2006 for the Braves. Butler has logged 333 big league games at first base.
"We went into it last year with Billy on the bench, but the way Billy's swinging the bat this year we can't afford to do that," Yost said. "We've got to have Billy on the field during these National League games."
If Hosmer and Francoeur converge on a fly ball in the right-center-field gap, Hosmer knows who'll be in charge.
"Frenchy," Hosmer said. "Any ball he can get, he's going to go ahead and take care of that. If I'm out there, I'll just handle the line and anything he can't get to out there."
With speedy center fielder Jarrod Dyson out of the starting lineup, the defense is likely to suffer.
"Some," Yost said. "But we'll switch out in the seventh inning or so, depending on the situations. We'll have all our pinch-hit priorities set and our defensive switches set."