Youkilis, 34, woke up with numbness in his right foot and will see a specialist in the coming days. He missed a few days earlier this week with a stiff back after sliding feet-first into first base.
In 11 games between injuries, Youkilis went 6-for-41 (.146) with three doubles, four walks and 13 strikeouts. He is hitting .219/.305/.343 (77 OPS+) with two home runs in 118 total plate appearances this year, his first in New York.
In other roster news, the Yankees have recalled outfielder Thomas Neal and right-hander Chris Bootcheck from Triple-A. Right-hander Adam Warren was sent down to clear a roster spot. Bootcheck last pitched in the big leagues in 2009.