Shorter sets, shot clock to be tested

The ATP will test radical rule changes including shorter sets at the inaugural end-of-season tennis finals for up-and-coming players in Milan, the sport's ruling body announced on Tuesday.

The tournament, featuring the world's best players aged 21 and under, will introduce first-to-four-game sets, with tie-breaks played at 3-3.

The best-of-five-set matches "do not alter the number of games required to win a match (12) from the traditional (best-of-three-set) scoring format," the ATP said.