STAR Hawthorn defender Jarman Impey's career-best season is over, with the club confirming he will undergo a knee reconstruction this week.

Impey hyperextended his right knee as he landed from a marking contest early in the second quarter of Hawthorn's 24-point victory over Geelong on Sunday, and he had to be helped from the field.

The Hawks were hopeful he had avoided tearing his anterior cruciate ligament, but scans on Monday confirmed the worst.

"It's obviously really disappointing for both Jarman and the club, but he is in high spirits and remaining positive," Hawthorn football boss Graham Wright said.

"Jarman is such a valuable player for us and has been in impressive form.

"He is a strong, resilient character and we're confident he will approach his rehab program with intent and professionalism."

The setback comes as the club mounts a serious finals challenge, having won three straight matches to move within one game of the top eight with five rounds to go.

HAWKS UPSET CATS Check out the match report and all the stats

Impey was in outstanding form before the injury, averaging 16.5 disposals and almost two intercept marks, while using his breakneck pace to be a weapon off half-back.

Jarman Impey clutches at his knee after landing awkwardly at the MCG. Picture: AFL Photos

He may even be leading the Hawks' best and fairest award, or at least be pushing in-form winger Ricky Henderson.

How coach Alastair Clarkson adapts to Impey's absence will be interesting, given the former Power speedster's rare athletic traits.

Dan Howe returned to his backline roots as a late inclusion for another defender, Grant Birchall (soreness), against the Cats and may remain there with this news.

BARRETT Get ready for the biggest game of the year

Other options in the VFL – none of them like for like – include David Mirra, Kaiden Brand and Teia Miles.

Former Sun Jack Scrimshaw (knee), an intercept specialist, hasn't played since round 10 but will also come into calculations once he returns to full fitness.