Don won the world title in 2006
Alistair Brownlee, Tim Don and William Clarke all achieved the Olympic triathlon qualification criteria at the Madrid World Cup meeting in Spain.
Brownlee, the 2006 world junior champion, led the British trio home in third, with former senior world champion Don fourth and Clarke sixth.
Helen Tucker and Hollie Avil, the 2007 world junior champion, secured the criteria for the women's team.
Tucker was second and 18-year-old Avil fourth in the women's race in Madrid.
"I can't believe it. After my injuries I wasn't able to do much hard running but I felt awesome," said Tucker from Bridgend, who has battled injuries for the last two years.
"I"ve made the Olympic selection criteria so we'll wait to see when they announce the team but I fully expect to be on that pontoon in Beijing," said Avil.
The British team for the Olympics will be confirmed on 26 June.