"Thomas has a chronic groin condition," Warriors doctor John Mayhew said. "It's one of the most difficult injuries to manage - groin pain is a minefield - and is taking time to settle down."
The club are optimistic Leuluai will be back by the end of June.
"We expect he will be back this season. He might be playing in three or four weeks but nothing can be ruled out," Mayhew said. "I would say that [not playing again] this season is a possibility rather than a probability."
Leuluai's condition - osteitis pubis - is one of the most complex and least understood afflictions. Various tests have ruled out other conditions (such as sports hernia, infection or adductor damage) allowing the medical staff to narrow their focus. Unfortunately, the best treatment for this condition is rest - extremely difficult for a sportsperson - and operations generally don't work.
The condition often hits halves, first-fives and hookers, either from kicking actions or the repeated sideways passing actions. Grant Fox suffered from this injury during his career, as did fellow former All Black Paul McGahan, while ex-Warriors and Kiwis fullback Brent Webb had to be managed carefully through his last season at Mt Smart.
It's a concerning situation for the club. Aside from his all-round skill set, Leuluai is one of the mentally toughest players in the NRL. He is an ultimate professional, a leader in the halves and the best secondary option at hooker. His ongoing absence also puts pressure on Chad Townsend - who is improving every week - to become a fixture rather than a back-up.
"It just encourages me to work even harder," Townsend said. "I'm sure Thomas will be back at some stage but I will do my best to make it hard for the coaching staff."
The club maintain Leuluai didn't come back too early this year - "he passed the tests, he was ready," Mayhew said - but maybe the exertions of last year caught up with him, especially the constant battles in a losing side during the first half of the season. Leuluai is currently doing light training on a treadmill.