HAWTHORN defender Grant Birchall will miss the next 4-6 weeks after suffering a knee injury during training last week.

The three-time premiership player suffered damage to his medial ligament while participating in a pre-season tackling drill.

Birchall will begin a running program on Monday but won't be available for Hawthorn's opening NAB Challenge game against Collingwood in Tasmania on 26 February.

He is, however, expected to be available towards the end of the NAB Challenge series ahead of the club's Round 1 blockbuster against Geelong on Easter Monday.

One of Hawthorn's elite ball winners, Birchall enjoyed an outstanding 2014 season where he was one of just four Hawks to play every game.

He averaged 23.6 disposals in his 25 games and was recognised for his excellent season by finishing second in the Peter Crimmins Medal.