Collins failed to recover in time from a long term groin injury forcing the 2003 world champion to give up hope of competing here.

Collins is only recently back to full-time training and his presence in Melbourne for the Games which started on Thursday was always in doubt. The 29-year-old St Kitts and Nevis sprinter picked up the injury at last summer's world championships in Helsinki.

Collins failed to defend his global title in Helsinki, but his bronze medal behind Justin Gatlin and Michael Frater again emphasised his world class ability and proved him to be the man for the big occasion.

He only returned to serious training in January and has set his sights on preparing for the summer season - and the lucrative IAAF Golden League and Grand Prix circuits.

His withdrawal along with the absence of the top Americans - because they are not members of the Commonwealth - gives Powell a great chance of capturing not only his first ever major title but also his first ever individual medal.

Despite his breaking the world record in Athens last year with a time of 9.77 seconds the 23-year-old has consistently failed to live up to his reputation at championships.

He was disqualified at the 2003 world championships in the quarter-finals, finished out of the medals in the 2004 Olympic final and was injured and missed the 2005 world championships, though he claimed afterwards that he would have won the title.

His main opposition now should come from compatriot Frater and Trinidadian duo Darrel Brown and Marc Burns.