HIGHLIGHTS-Day Four at the Australian Open

"He's a very good mover. Good athlete. He wins. He knows how to win matches. He understands the game well and he gets the most out of his game.

"If I play well, I got a good chance obviously. But, you know, he's the sort of player that if your level's not quite there, he'll make it very tough for you, as he did when I played him at the French Open. I was in a bit of trouble against him there."

Israel's Dudi Sela progressed to the third round with a 4-6 6-3 6-3 7-6(4) win over Spain's Fernando Verdasco, who had knocked out 14-time Grand Slam winner Rafa Nadal in his previous match.

This is a first Thursday day record crowd with 48,691 in attendance at Melbourne Park, comfortably beating the previous record set in 2012 of 47,471.

American 15th seed and last year's Australian Open semi-finalist Madison Keys battled her way past Kazakhstan's Yaroslava Shvedova 6-7(4) 6-3 6-3 in a two-hour contest. She will face 20th seed Ana Ivanovic of Serbia in round three.

Canadian 13th seed Milos Raonic is through to round three after he served 24 aces during his 7-6(6) 7-6(5) 7-5 win over Spain's Tommy Robredo. Raonic next plays Serbia's Viktor Troicki.

Germany's Laura Siegemund rallied from a set down to progress to round three with a 3-6 7-6(5) 6-4 win over Serbian 19th seed and former world number one Jelena Jankovic.

"I'm working on my body. I'm just working on my overall body to be healthy... and I believe I'm on the right track.

"I want to keep working hard, because it's still not where I want to be. Honestly, I think I'm feeling in the best shape body-wise, you know, spirit-wise, everything-wise."

Czech Republic's Denisa Allertova dumps German 30th seed Sabine Lisicki from the tournament with a 6-3 2-6 6-4 win. She will take on Johanna Konta of Britain in third round.

Third seed Garbine Muguruza continued her impressive start with a 6-4 6-2 demolition of Belgian Kirtsten Flipkens at Rod Laver Arena.

"I'm extremely happy with today, Kirsten has a really different game and it can be tricky so I'm very happy to be in the third round," Muguruza said courtside.

"Just happy to be here and playing great tennis."

Former finalist Ana Ivanovic was shaken up when play was held up for over 20 minutes at Rod Laver Arena after a female spectator at Rod Laver Arena fell down the stairs.

"It was actually good that we had to wait a little bit because I was really shaking, because I could imagine and it was not so nice," she said. "Then they told us she was bleeding, so I hope she's well."

Tenth seed John Isner grinds down Spaniard Marcel Granollers 6-3 7-6(6) 7-6(6) at Hisense Arena. The towering American fires 20 aces in the win to set up a match with either Feliciano Lopez or Guido Pella.

"My serve bailed me out today," Isner said courtside.

Eighteen-year-old Naomi Osaka dumps Ukrainian 18th seed Elina Svitolina from the tournament with a 6-4 6-4 win. A match-up with twice champion Victoria Azarenka awaits.