Victorino was removed from Saturday's 4-3 win against the Royals after experiencing tightening in his lower back and was pinch run for by Jonny Gomes, who scored on Daniel Nava's game-winning, three-run home run.
"He feels improved from yesterday and last night," manager John Farrell said before Sunday's 4-2 Game 1 loss. "Yet there's still some tightness in the lower back. He's day to day, so we'll hold him to sit out and he'll continue to get treatment."
Nava received the start in right field and batted second, with Gomes playing left field and batting ninth against Royals right-hander Ervin Santana.
Farrell also didn't rule out having Victorino available for Game 2 on Sunday night.
"We'll find out later in the day," Farrel said, "but he's not ready for Game 1."
Victorino was 0-for-2 with a sacrifice hit before leaving in Saturday's game. He'd reached base in 14 of the Red Sox's first 16 games and secured hits in 11 games while sporting a .377 on-base percentage.
Also Sunday, the Red Sox officially recalled right-handed pitcher Allen Webster from Triple-A Pawtucket to start the nightcap of the doubleheader.
Webster, who was acquired from the Los Angeles Dodgers in August as part of the nine-player trade that sent Josh Beckett, Adrian Gonzalez, Carl Crawford and Nick Punto westward, will make his major league debut.
No corresponding roster move was required as Webster was added as the 26th man on the active roster, part of a provision on days of doubleheaders.
Webster, 23, has made two starts for the PawSox, but had not factored in a decision while carrying a 0.90 ERA in 10 innings pitched.