Career Highlights: The 18-year-old Aman is a rising star in middle-distance running, and could be the biggest challenger to 800-meter juggernaut David Rudisha in London. The Ethiopian ended Rudisha's 34-race winning streak in the event at a rainy meet in Milan last September, just after setting a personal best of 1:43.37. Aman followed up his breakout 2011 season by winning the 800 at the world indoor championships in March, although Rudisha wasn't there. Aman will try to bounce back outdoors in London after a disappointing finish at the 2011 worlds. He won his semifinal heat, but struggled to a last-place finish in the final as Rudisha won gold. It remains to be seen if Aman is ready to make an impact on track's biggest stage following an impressive youth career that included a gold medal in the 1,000 meters at the 2010 Youth Olympics. He won silver in the 800 at the 2011 world youth championships.