Beltran, who said on Saturday that he could play through the pain as long as it wouldn't aggravate the injury, had a different opinion following Sunday's 10-6 loss to the Rays.
"I don't feel I can play a lot of games the way it felt today," Beltran said. "I'm a little bit worried, to be honest, because the way it was today, it was painful."
Beltran initially injured the knee in Los Angeles during a series in mid-May. He was the designated hitter for three games in Boston before sitting out two games against the Nationals on May 26-27. The center fielder was diagnosed with a bone bruise below his right knee and was given a cortisone shot to help alleviate the pain.
That had worked until this weekend.
"It's a sharp pain in the knee that keeps me from running full speed," Beltran said, adding that it affected him most while running and batting from the right side of the plate. "Hopefully tomorrow comes out well."
At times, Beltran looked tentative in the field Sunday, but he did let loose to make a sliding catch in the seventh to strand the bases loaded and keep the Mets in the game. He was 2-for-4 at the plate and is still in the top five in the National League in hitting with a .336 average.
Tim Britton is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.