HAWTHORN midfielder Brad Sewell is expected to miss at least the next month of football after injuring his hamstring during Friday night's loss to North Melbourne.

The 30-year-old was subbed out of the match early in the first term with the injury, and scans on Saturday have since revealed a low grade strain.

Hawthorn's football operations boss Chris Fagan said Sewell would be sidelined for 3-4 weeks.

"Brad will get straight back into a solid rehabilitation block with our medical staff and hopefully return within the next month to contribute to the back end of our season," Fagan said.

This is the second time Sewell has suffered a hamstring injury in 2014.

The veteran midfielder tore his hamstring in the Hawks' final practice match against Melbourne in early March, and did not return to the senior side until round 10, after experiencing a minor setback whilst playing in the VFL in April.