MILWAUKEE (AP) _ Bucks forward Darvin Ham will miss 3-4 months after left foot surgery Monday, a blow to Milwaukee's hopes of challenging the top teams in the Eastern Conference.

Ham, the Bucks' defensive leader, was injured while going after an offensive rebound against Detroit in the third quarter Saturday night. He came down on another player's foot and had to be helped to the locker room.

Originally, the Bucks said the injury was only a sprain, and coach George Karl said he didn't expect Ham to miss much time, if any. Ham said he would play against the New York Knicks on Tuesday night.

But Ham did need surgery to reposition displaced bones in the foot.

He started two of the team's first three games at power forward, while Jason Caffey became more familiar with the offense. Caffey, obtained from Golden State in a three-way deal June 27, will return to the starting lineup.

Ham averaged 6 points, 6.3 rebounds and 1.7 blocks in three games. Against Dallas in the season opener, Ham matched a career-high with 13 rebounds.

The fourth-year pro averaged a career-high 5.1 points, 4.9 rebounds and 1.2 assists last year, then signed a free-agent contract in the offseason to remain in Milwaukee. He was a key defensive component for the Bucks, considered among the contenders in the diluted East.

The Bucks' big four _ Glenn Robinson, Sam Cassell, Ray Allen and Tim Thomas _ are all finesse players.

Ham, Scott Williams and Ervin Johnson were being counted on to provide a physical presence on defense.

``They do things that don't show up in the stats,'' Robinson said. ``Darvin plays hard every game and is very physical.''

The Bucks did not immediately say who will replace Ham on the active roster.