MELBOURNE, Australia — Nearly a week into the Australian Open, the only major surprise is that there have been, well, not many surprises at all.

The year’s first Grand Slam is historically fraught with injury withdrawals or top players not yet up to speed in the new season and losing in the first few rounds.

But with the third round complete for the leading players at Melbourne Park, only one of the first eight men’s seeds did not advance: No. 6 Juan Martin del Potro. Six of the eight top women were through.

Second-seeded Roger Federer was the last of the main contenders to advance to the fourth round, beating Australian Bernard Tomic 6-4, 7-6 (5), 6-1. Federer trailed 4-1 in the tiebreaker but rallied for six of the next seven points in front of a full house at the 15,000-seat Rod Laver Arena.

“I had a few more chances than he did, but I thought the tiebreaker was going to go his way,” said Federer. “I think overall we played a great match, he really got the best out of me tonight.”

The four-time Australian Open champion will next play big-serving Canadian Milos Raonic, who beat No. 17 Philipp Kohlschreiber of Germany 7-6 (4), 6-3, 6-4.

Del Potro was a 6-3, 6-3, 6-7 (3), 3-6, 6-3 loser to France’s Jeremy Chardy earlier Saturday in the biggest upset so far in this tournament.

Top-seeded Novak Djokovic and No. 3 Andy Murray haven’t dropped a set in three matches, although Murray had his difficult moments in Saturday’s 6-3, 6-4, 7-5 win over Ricardas Berankis.

In women’s play, top-seeded Victoria Azarenka had her problems against injury-affected American Jamie Hampton and needed three sets to advance on Saturday, but No. 3 Serena Williams has not dropped a set despite an injured right ankle.

“There’s always two ways — your opponent plays good and you can also make your opponent look good,” Azarenka said after her 6-4, 4-6. 6-2 win.