WESTERN Bulldog Robert Murphy's right knee problems will stop him running before January, putting the early part of his side’s NAB Cup campaign in doubt.

Murphy had surgery back on September 25 to repair his patella tendon, but the nature of the surgery means he needs a full three months of rehabilitation.

Murphy had a knee reconstruction in 2006, but that was his left knee.

Murphy injured the knee in round five against the Tigers, but he played on before another setback late in the regular season, but managed to complete the finals series.

"He can't do any weight-bearing activity until post Christmas," Bulldogs football manager James Fantasia told the Herald Sun.

Brownlow Medallist Adam Cooney also had knee surgery in early October, but keyhole surgery means a four to six-week recovery period allowing an uninterrupted pre-season.