TOKYO — Serbia booked its ticket to the London Olympics Saturday, beating Iran to secure top spot in the men’s volleyball qualifying tournament in Tokyo. With a 30-28, 30-28, 25-22 victory over its nearest rival, Serbia chalked up a sixth straight win against no defeats for an unbeatable 18 points in the eight-team round robin competition. The winner of the tournament and the best-placed Asian team qualify for the London Games, starting next month. In the Olympics, Serbia will join Russia, Poland, Brazil, Italy, Tunisia, the US, Argentina and host Britain. — AFP