Great Britain suffered a double setback at the World Championships in Perth today with Southampton-born Iain Percy suffering a back injury and Ben Rhodes forced to pull out due to a rib problem.

Percy was left in agony when his back gave out while he and teammate Andrew Simpson were well placed in the defence of their World Championship crown in the first race of the day for the Star fleet.

The British team was already reeling from the news that Rhodes and his team-mate Stevie Morrison had been forced to retire from the 49er event after Rhodes succumbed to an injury picked up yesterday.

Percy's injury was so serious he was left in tears, while his inability to assist Simpson meant the pair picked up their second yellow flag of the regatta.

The 2008 Olympic gold medallists, overnight leaders by 12 points, were third in the race when injury hit, and Simpson said: "Iain was in tears, crying, and really in a bad way.

"I haven't actually ever seen him that bad before. It's not very nice when you see a grown man cry and he was in absolute agony.

"We tried to make the plan to try and literally just get around the course and we had a good lead on fourth place - the three boats at the front were making a nice separation. Then somehow, with Iain basically in a paralysed way down the run, we got a yellow flag which was our second one of the regatta.

"It was very surprising, very frustrating and obviously we had to pull out of the race. There was nothing more we could do and Iain couldn't sail the next race."