The Phillies said Ruiz, who leads the National League with a .472 on-base percentage, is day-to-day.
"We have an off-day tomorrow, so this is good news," Phillies assistant general manager Scott Proefrock said. "We'll just have to play it by ear, but it's not a DL situation."
Proefrock said they have no plans to have a catcher from their farm system fly to Milwaukee in case Ruiz is unable to play Friday against the Brewers. The Phillies only have one other catcher on the 25-man roster: Paul Hoover. They placed catcher Brian Schneider on the 15-day disabled list Sunday with a strained left Achilles.
Jayson Werth is believed to be the team's emergency catcher if Hoover gets hurt -- not that Phillies manager Charlie Manuel wanted to talk about it.
"We'll wait until somebody else gets hurt," Manuel said. "That might happen. There's a good chance, though."
Werth didn't want to talk about it, either.
"Shhhh," he said. "Shhhh."
Ruiz injured his knee trying to tag out Carlos Gonzalez at the plate on a sacrifice fly in the first inning. Ruiz stayed in the game, and left after he ran from first to third base in the fourth.
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.