"Kelly is going to DH tomorrow," Collins said. "We'll worry about Wednesday when it comes."
In 10 games, Mets DHs combined to hit .175 (7-for-40) with one home run and two RBIs. Righty-hitting Michael Cuddyer had the most turns as a DH, going 3-for-19. Johnson has logged just six at-bats this postseason, making five of those appearances as a pinch-hitter and notching one hit.
"I think the adrenaline of this World Series is going to be enough," Johnson said. "I'll obviously be able to have an at-bat to build on to the next one, rather than just to pinch-hit where you have to just throw it away. We'll see what happens. The game will play out, whether there's guys on when I come up or a situation to be had, I'll be ready."
Johnson is 4-for-14 (.286) with a double and two RBIs lifetime vs. the Royals' Game 1 starter, right-hander Edinson Volquez, though they've only faced each other twice in the last five years.
"To me, that makes it a little bit irrelevant," Johnson said. "I guess if there's anything, there's going to be some comfort there in having seen him if I look at some video. At least I'll be able to see how he throws and how he attacked me. It's been a while, but there will be something there."
Johnson, whose 10-year career has included stints with four AL clubs, has considerable experience as a DH. Lifetime in that role, he is 19-for-91 (.209), with three home runs.
Collins said that the Royals' decision to start Volquez and not Johnny Cueto was a factor discussed.
"We looked at all the possibilities," Collins said. "And if Cueto was starting, we were looking at perhaps somebody else, because his numbers against lefties are pretty good. We thought tomorrow night that Kelly gave us our best opportunity and if we need to make changes, we will."
Cueto, a right-hander who features an excellent changeup, has held lefties to a .672 OPS in his career and righties to a .692 mark. He's slated to start Game 2.
Volquez doesn't have a discernible split, but he did allow 10 of his 16 homers this year to left-handed hitters. Johnson, meanwhile, hit 13 of his 14 homers this season against southpaws, and slugged 80 points higher against them than he did righties. Collins is hoping he'll give the Mets another power threat.
One alternative was that the Mets could have emphasized defense by starting Juan Lagares in center field while using Michael Conforto as the DH, with Yoenis Cespedes and Curtis Granderson stationed in the outfield corners.
"We're pretty happy with our outfield defense," Collins said. "This is a big park, like ours. I think Yoenis has shown that he can play center field. And if we need to make moves, we'll make moves later in the game."
The Mets' last designated hitter in a World Series game was Lenny Harris, who batted seventh in a lineup against Roger Clemens for Game 2 of the 2000 Fall Classic vs. the Yankees at Yankee Stadium.