Reigning double world champion Usain Bolt heads Jamaica's team for the 2011 athletics World Championships, a squad that inclues three more defending champions but not provisionally suspended Steve Mullings. Bolt, winner of the men's 100m and 200m in world record times of 9.58sec and 19.19, in Berlin two years ago, will be joined in Jamaica's strong 50-member delegation by fellow defending champions Shelly-Ann Fraser-Pryce, who took the women's 100m, women's 400m hurdles champion Melaine Walker and Brigitte Foster-Hylton, the women's 100m hurdles winner. Asafa Powell, who is still in search of his first global title in the men's 100m, joins Bolt in the event along with Yohan Blake. Other gold medal contenders include Veronica Campbell-Brown, who is vying for her first World Championships sprint double, 400m hurdles favourite Kaliese Spencer and 800m runner Kenia Sinclair. Nesta Carter is expected to be a medal contender in the 100m in place of Mullings, who returned a positive drug test sample at the Jamaican trials. At 400 meters, Jermaine Gonzales, Kerron Stewart, and Rosemarie Whyte are also very strong contenders. Isa Phillips, who ran 48.94 on the weekend in Germany to be the fastest Jamaican this season, was included at the last minute ahead of the third place finisher at the trials — Roxroy Cato, who had only the “B” qualifying standard. Phillips had finished fifth at the National Championships in June. The World Championships are to be held in Daegu, South Korea, from Aug. 27-Sept. 4. Eight champs in US team The United States submitted its final roster to the IAAF Monday for the 2011 athletics World Championships, a team including eight reigning world title holders. The roster includes Allyson Felix, the reigning 200m world champion who will attempt a 200m-400m double at this year's worlds in Daegu, South Korea. In the 400m at Daegu, she will compete against Sanya Richards-Ross, the American record-holder in the 400m who will defend her world title in the event. Monday's final roster included a couple of changes from last week's preliminary squad, including the addition of Jessica Beard in place of the injured Debbie Dunn in the women's 400m. Michael Rodgers, facing a doping ruling after a positive test for a banned stimulant, remained on the roster in the 100m.