VETERAN Hawthorn defender Grant Birchall might not be back until round 18 as he continues his gradual build-up from a nagging knee injury. 

Birchall hasn't been sighted at AFL level since round 15 last year after suffering a setback with his knee in March.  

The 30-year-old was recently placed on the Hawks' long-term injury list, with coach Alastair Clarkson declaring Birchall was progressing well as he undergoes a mini pre-season before returning to football.

Clarkson hoped Birchall would be back either side of the round 12 bye, however vice-captain Isaac Smith indicated the four-time premiership Hawk might only return to the senior side for the run home. 

"'Birch' has had a pretty tough 12 to 18 months and hasn't been able to really get going," Smith told SEN radio. 

"I think they're saying he'll probably be later in the year after the bye, maybe around round 17 or 18.

"It will be nice to get him back and if we're in a position to play finals he's a pretty big asset for us."

Birchall, who only managed five games last year due to a fractured jaw and his PCL problems, isn't the only important Hawk on the sidelines.   

Electric star Cyril Rioli is about a month away from his comeback from a medial ligament issue, while pressure forward Paul Puopolo will be sidelined for another two weeks at least by a hamstring problem.

Hawthorn faces arch rival Essendon at the MCG this Saturday afternoon.