DASHING Lions utility Ash McGrath will go under the knife tomorrow to repair a hamstring tendon injury that will keep him out for the remainder of the season.

The 29-year-old started the year in defence but was switched forward against the Bulldogs in round 13 and responded with a match-winning five goals.

He was on track for a repeat the following week against Melbourne, bagging three before sustaining the injury.

Meanwhile West Coast defender Beau Waters will miss a month after having an arthroscopy on his knee yesterday, and Adelaide big man Shaun McKernan is set to miss six weeks with facial fractures suffered in a head clash against Port Adelaide on Saturday night.

Scans yesterday showed three separate fractures, although a club official said McKernan would not need surgery.