Isi Tu'ivai has called it quits. After six seasons of rugby in Hong Kong, the 'Tongan torpedo' feels he has run himself into the ground. 'I'm retiring. I have informed the coaches that I'm pulling out of sevens and 15s rugby,' said Tu'ivai. The Valley and Hong Kong star cited increasing work commitments as his reason for quitting. Tu'ivai, the manager of a fitness club in Causeway Bay, said: 'Trying to play international rugby and having to work at the same time did not fit in for me. Mentally, I was not prepared. I'm out of rugby. Full stop.' Tu'ivai, 28, said he had arrived at the decision last Sunday - soon after the SAR had disappointingly bowed out of the Hong Kong Sevens Plate competition, losing to Japan in the quarter-finals. 'I was two miles behind everything I would normally have done . . . all this stemmed from a lack of preparation. I wanted to play competitively, but my work prevents me from doing that. 'I can't give my 110 per cent and I feel it is only fair that I retire,' he added. So after more than 50 games for Hong Kong at 15-a-side, including two Asian Rugby Football Tournaments, and seven appearances at the Sevens (five for Hong Kong and two for Tonga), Tu'ivai has decided that he should go out on his own steam - rather than be ignored in future selections. His absence will be a huge loss for Hong Kong, especially when the Asian tournament comes around in Singapore in October. Hong Kong rugby has already lost veteran Stuart Krohn. Vaughan Going will soon be gone. And now Tu'ivai. All three players the SAR would have needed in their bid to qualify for the 1999 World Cup.