The 23-year-old Australian- now entering the final season of his three-year contract at the Dutch side - had been experiencing pain in the groin, similar to the problem he suffered last season.

Utrecht's medical staff ran tests on the young Socceroo  and have now put him on an individual program with a view to returning to full fitness in six weeks.

The injury means Zullo will face a major disruption to his pre-season training and miss the start of the 2012-13 Eredivisie season, which is due to begin on August 10.

"We have a training program for Michael now, hopefully to once and for all fix this injury," said club doctor Niels Wijne.

"It is important now for him to be recovering well. He will work on an individual program, which means he will miss the training camp.”

Zullo managed just 13 appearances for Utrecht last term, have played just six times in an injury-ravaged first season in the Netherlands.