The Giants took a 3-0 lead in the seven-game series after Saturday night's Game 3 win.
"You try to trick yourself into thinking it's another game, but you know what's going on," Cain said. "Your mind and your body, they know what's going on. They know it's going to be a big game in the World Series."
Both teams probably like their chances with the starters they'll have in the game.
Scherzer, who was 16-7 in the regular season with 231 strikeouts that trailed only teammate Justin Verlander's baseball-leading total, is 0-1 with an 0.82 ERA this postseason.
Cain, meanwhile, hasn't been quite as sharp in the playoffs as he was during the regular season.
He is 2-2 with a 3.52 ERA in the postseason.
Bud Selig presented Miguel Cabrera with an actual crown Saturday, recognizing the Triple Crown he won this season, and announced that the Tigers slugger won the AL's Hank Aaron Award.
For the first time, both winners of the award that recognizes the top offensive players in each league were getting ready to play in the same World Series.
After Cabrera posed for pictures and made a statement, he went to get ready for Game 3. Moments later, Giants catcher Buster Posey was honored for being the NL's Hank Aaron Award winner.