Roger Federer and Roddick cruise through

World number two Roger Federer and American favourite Andy Roddick both cruise through in straight sets in their third-round matches at the Miami Masters.

Roddick survived a gruelling first set tiebreak against Russian Dmitry Tursunov, which he won 11-9, before going on to ease through the second set 6-2.

Federer enjoyed a routine 6-4 6-1 win over German Nicolas Kiefer but will face a surprise opponent in the fourth round after 15th-ranked Spaniard Tommy Robredo lost 7-5 6-3 to American qualifier Taylor Dent.

Dent's career looked finished in 2007 after he spent most of the year in a cast following a serious back injury, but has come back impressively.