Grudzielanek revealed on Wednesday that he has a torn deltoid ligament on the left side of his right ankle.
"I'd be pressed to get back this year," he said,
Grudzielanek was injured Friday night in a collision with first baseman Ross Gload as they were chasing a popup by the White Sox Juan Uribe into the outfield.
"I saw [right fielder Mark Teahen] way back there and said, 'He's not catching it,' so I went after it," Grudzielanek said. "I didn't think Rossie would be there at all."
Gload ducked down, trying to avoid contact, but banged into his teammate's ankle. Grudzielanek left the game and an MRI on Saturday showed the tear.
After seeing a videotape of the play, doctors told Grudzielanek they were surprised that it wasn't a compound fracture.
"Luckily, I don't need surgery, but the fibers are hanging there," he said.
Grudzielanek was told that the injury will heal on its own, but that he'd be out four to six weeks. That could take him down to the last couple of weeks of the season and create a doubtful scenario for his return to play this year.
Manager Trey Hillman said that the Royals will know more in about two weeks, but also said that Grudzielanek's missing the rest of the season is "a definite possibility."
"He's got to consider, as do we, if it's best for his body to force the issue and try to get back with, effectively, maybe only two weeks of the season left," Hillman said.
Grudzielanek plans to return to his California home for a while to recuperate and undergo treatment.
"I bounce back fast from injuries and we'll see how it goes," he said.
Grudzielanek, 38, said his season might be over, but not his career.
"Oh, I'll play another year," he said. "Maybe two."
He can become a free agent and the Royals have not approached him about coming back. So, realistically, the Kansas City portion of his career could be over.
This season he's batting .299 in 86 games and, though he has modest totals of three homers and 24 RBIs, he's batted third in the lineup recently.
This is Grudzielanek's third season in K.C. Last year, he batted .302 and was named Royals Player of the Year. In 2006, he hit .297 and won his first Gold Glove. He's established himself as a team leader and a solid veteran presence on a youthful club.
"Any time you lose a veteran in the middle of your field, it's a big loss," Hillman said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.