Unflappable, poised, experienced and relentless, Andy Roddick went about his work on Sunday.

Three heavyweights have been joined by upset specialist Tomas Berdych of Czechoslovakia to battle in the semifinals of the Men’s Draw in Miami at the Sony Ericsson on Friday.

Roger Federer ran into some unexpected resistance at the hands of Frenchman Florent Serra but the top seed managed to hold on for a 7-6 (2), 7-6 (3) third round victory at the Sony Ericsson Miami Open on Monday.

The cream is rising to the top at the Sony Ericsson Miami Open. Second seed Princess Caroline Wozniacki of Denmark withstood an early match challenge from Russian glamour girl Maria kirilenko, the 32 seed, 1-6, 6-1, 6-4 to lead a bevy of highly seeded players into the round of 16.