Cornthwaite, 23, has been absent from Reds training for the past 10 days and club doctor James Ilic said test results confirmed that Cornthwaite had contracted the latest flu strain.

However despite the setback, Cornthwaite is said to be in the final stages of recovery and is likely to be back with the rest of United's squad next week.

Ilic expects Cornthwaite will be cleared and ready to return to training on Monday, putting him in the frame to possibly face Melbourne Victory in their  pre-season friendly on Sunday, July 26 at Aurora Stadium in Launceston.

Young Reds midfielder Joe Costa has also been missing from action for over a week after being laid up with illness, however tests have cleared him of swine flu.