Nishikori, Muller knock out remaining American men, more Day 6 results

MELBOURNE -- Catch up on all of the action from the Australian Open on Saturday that you may have missed while you were sleeping: No American man reaches the

MELBOURNE -- Catch up on all of the action from the Australian Open on Saturday that you may have missed while you were sleeping:

No American man reaches the fourth round for the fourth straight year

Mailbag: Analyzing Federer's early AusOpen loss to No. 46 Seppi

John Isner and Steve Johnson were the last two American standing

Serena and Venus Williams rally from a set down to advance

The sisters had to work much harder than either would have liked, but for the first time since 2011 Wimbledon, both Serena and Venus advanced to the fourth round of a Slam. Serena shook off a sluggish start to defeat No. 26 Elina Svitolina 4-6, 6-2, 6-0, while Venus rallied from 2-5 down in the second set to defeat No. 33 Camila Giorgi 4-6, 7-6 (3), 6-1. The win puts Venus on the verge of cracking back into the Top 10 for the first time since the spring of 2010. 

"For me, I always believe in my ability, but sometimes you don't get results for whichever reason," Venus said. "I think as long as I know that I've got it in me, that's it. I've won big. It's not like I haven't done it before. For me, I like to win titles. I like to win titles, whether it's a smaller event or a big event. That's what I play for. So, yes, great, it's great to be in the second week. But is fourth round my goal when I come to these tournaments? No."

Venus will play No. 6 Agnieszka Radwanska on Monday. Serena earns a rematch against No. 24 Garbine Muguruza, who defeated her in the second round of the French Open last year. "As angry as I was, it was the best loss I had the whole year last year," Serena said. "Had a lot of them. But that one in particular made me realize what I needed to work on. It opened my eyes towards a lot of things. I was like, Oh, my gosh, if I don't change, then I'm going to be forever in the same position. It actually ended up helping me a lot."

Madison Brengle charges into the fourth round

Venus Williams is thriving in the midst of a career upswing at 34-years-old

The unheralded American from Dover, Delaware stormed into the fourth round with a 6-3, 6-2 win over CoCo Vandeweghe. The win propels her into the Top 50 for the first time. She was once again solid and consistent off the ground against Vandeweghe and showed tremendous poise for a player who fell in qualifying in each of the last six years here in Melbourne. She's now 14-2 in main draw and qualifying matches to start 2015. So how are her parents doing following along from home? Her mother can't stop talking about the towels and her father actually went to sleep instead of watching her match on Saturday. Will he tune in on Monday when a Slam quarterfinal is on the line?

"I'm not going to put him through that," Brengle said. "If he wants to watch that afterwards...No, I think he'll be too nervous. My mom will watch. My dad can hear the recap from her. That will be fine."

Madison Keys shocks No. 4 Petra Kvitova

Madison Keys stuns No. 4 Petra Kvitova to advance to round of 16

Four U.S. women will advance to the fourth round after 19-year-old Keys earned the biggest win of her career on Saturday night, defeating No. 4 seed Kvitova 6-4, 7-5. Keys will play against fellow American Brengle in the round of 16 on Monday, who she beat in a 2012 U.S. Open qualifier in their only head-to-head matchup.

Novak Djokovic and Stan Wawrinka cruise

No problems for the top seeds in the top half of the draw. Djokovic beat Fernando Verdsasco 7-6 (8), 6-3, 6-4, and Wawrinka beat Jarkko Nieminen 6-4, 6-2, 6-4. Djokovic will play Muller next and Wawrinka will play Guillermo Garcia-Lopez. 

Watch out: Milos Raonic's form looks very good

The Canadian has backed up his level of play from the Brisbane International final and moved easily through the first three rounds in Melbourne. He beat Benjamin Becker 6-3, 6-3, 6-3 on Saturday. He's been broken just once in the tournament. He faces No. 12 Feliciano Lopez next. 

Photo of the day

Quinn Rooney/Getty Images

Photo of the day: Matrix edition

Hannah Peters/Getty Images

Vine of the day

Not a great second serve there, Fernando Verdasco

GIF of the day

[tweet=https://twitter.com/TheTennisNerds/status/558856055892226048]

Quote of the day

Q. Who will you pick up for the men's title since Roger is out?

SERENA WILLIAMS: I was rooting for Andy the whole time, so we'll see what happens.

Tweets of the day

[tweet=https://twitter.com/NickMcCarvel/status/558894012690481152]

[tweet=https://twitter.com/NickKyrgios/status/558926084709036032]

[tweet=https://twitter.com/darren_cahill/status/558901066234724352]

[tweet=https://twitter.com/andy_murray/status/558868086514651137]

[tweet=https://twitter.com/FortyDeuceTwits/status/558889828842881024]