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Andrew Brownbill, Associated Press
Switzerland's Roger Federer celebrates after winning the first set against Croatia's Ivo Karlovic during their third round match at the Australian Open tennis championship, in Melbourne, Australia, Friday, Jan. 20, 2012.

MELBOURNE, Australia — Roger Federer made the most of his rare opportunities Friday against the fastest serve in tennis, cashing in with some classic returns in a 7-6 (6), 7-5, 6-3 win over Ivo Karlovic to reach the fourth round of the Australian Open.

The four-time Australian Open champion fended off Karlovic's set point in the tiebreaker with a return that brought the 6-foot-10 Croatian to the net, then lobbed just over him.

Federer and Rafael Nadal are on the same side of the draw at a major for the first time since 2005 and could meet in the semifinals.

Second-ranked Nadal had a 6-2, 6-4, 6-2 win earlier Friday over Slovakia's Lukas Lacko to advance without dropping a set or showing any signs that a freak knee injury is bothering him.