There is optimism that Brogdon could return closer to the six-week mark, sources said, but that still would leave the Bucks without their starter until the postseason.
Brogdon, who has started all 64 games he has played this season for the Bucks, has missed a handful of games due to soreness related to his plantar fasciitis. Tony Snell often started in his absence.
Brogdon is averaging a career-best 15.6 points, 4.5 rebounds and 3.2 assists in 28.6 minutes per game this season. He is shooting 50.5 percent from the field, 42.6 percent from 3-point range and 92.8 percent from the free throw line, putting him in line to be just the eighth NBA player to have a 50-40-90 season. Steve Nash, Larry Bird, Reggie Miller, Stephen Curry, Kevin Durant, Dirk Nowitzki and Mark Price are the others.
The Bucks (52-17) currently hold the best record in the NBA and will face the Sixers on Sunday (3:30 p.m., ET). They have 13 regular-season games left, with their finale in three-plus weeks against the Thunder.