Australian Open Day Seven Highlights: Nadal cruises into quarters as Tsitsipas stuns Federer

Roger Federer's hopes of winning a third consecutive Australian Open title were crushed by 20-year-old Greek Stefanos Tsitsipas, who earned the biggest victory of his career to reach the quarter-finals on Sunday.

The 37-year-old Swiss committed 55 unforced errors and wasted all 12 of his break-point opportunities in a 6-7(11) 7-6(3) 7-5 7-6(5) defeat under the lights of Rod Laver Arena.

Tsitsipas, who won the ATP Next Gen Finals last year, will now face Roberto Bautista Agut for a place in the semi-finals.

"I'm the happiest man on earth right now, I can't describe it," Tsitsipas said.

.@StefTsitsipas has been idolising Roger Federer since the age of six.

At 20-years-old, he's speechless 😶#AusOpen pic.twitter.com/VOe2cfhzP0

— #AusOpen (@AustralianOpen) January 20, 2019

In the other big upset of the day, world number two Angelique Kerber was beaten 6-0 6-2 by American Danielle Collins, who made her main-draw debut at Melbourne Park this year.

Men's second seed Rafa Nadal continued his steady progress by defeating Czech Tomas Berdych 6-0 6-1 7-6(4).

The Spaniard will next meet world number 39 Frances Tiafoe, who celebrated his 21st birthday by overcoming Bulgarian Grigor Dimitrov 7-5 7-6(6) 6-7(1) 7-5.

Australian number one Ashleigh Barty displayed her title credentials as she powered past former world number one Maria Sharapova 4-6 6-1 6-4.

RUSSIAN PAVLYUCHENKOVA KNOCKS OUT STEPHENS

Anastasia Pavlyuchenkova fought back from a set down to dump former U.S. Open champion Sloane Stephens out of the tournament with a 6-7(3) 6-3 6-3 win at Rod Laver Arena, closing day seven of the tournament.

The unseeded Russian reached her second quarter-final at Melbourne Park and will now meet another American in Danielle Collins.

UPSET ALERT: Anastasia Pavlyuchenkova d. [5] Sloane Stephens in the fourth round of the #AusOpen, 6-7 (3), 6-3, 6-3. The American led by a set and a break in a match that ended at nearly 2:00 a.m. Melbourne time. pic.twitter.com/sLKSFsxeg4

— TENNIS.com (@Tennis) January 20, 2019

TSITSIPAS STUNS DEFENDING CHAMPION FEDERER

Two-time defending champion Roger Federer suffered a shock defeat by 20-year-old Greek Stefanos Tsitsipas in the fourth round in Rod Laver Arena.

"I'm the happiest man on Earth right now," Tsitsipas, who won 6-7(11) 7-6(3) 7-5 7-6(5), said at courtside.

"Roger is a legend of our sport he showed such good tennis over the years. It was very important to have an aggressive mindset.

"I've been idolising Roger since the age of six. Winning on Rod Laver Arena... I cannot even describe it."

⚡️ “Roger Federer is out of the Australian Open”https://t.co/skYYxY5JJy

— BBC Sport (@BBCSport) January 20, 2019

BAUTISTA AGUT DOWNS CILIC IN FIVE-SET THRILLER

Spain's Roberto Bautista Agut kept his composure in a tense five-set encounter to knock out 2018 runner-up Marin Cilic 6-7(6) 6-3 6-2 4-6 6-4 and reach his maiden Grand Slam quarter-final.

It was Bautista Agut's third five-set victory at Melbourne Park this week.

Roberto Bautista Agut is into the first Grand Slam quarterfinal of his career! The 30-year-old just beat Marin Cilic 6-7 (6), 6-3, 6-2, 4-6, 6-4 in a back-and-forth affair at the #AusOpen. That’s three five-set victories at this tournament alone. pic.twitter.com/6txbMoAPwU

— TENNIS.com (@Tennis) January 20, 2019

NADAL CRUISES INTO QUARTERS

Second seed Rafa Nadal produced a dominant display to beat Czech Tomas Berdych 6-0 6-1 7-6(4) in just over two hours on Rod Laver Arena.

Nadal will next face American Frances Tiafoe.

Vamos @RafaelNadal!

He def. #Berdych 6-0 6-1 7-6(4) to reach his ELEVENTH quarterfinal here in Melbourne.#AusOpen #GameSetMatch pic.twitter.com/schFsiNuYQ

— #AusOpen (@AustralianOpen) January 20, 2019

TIAFOE POWERS PAST DIMITROV ON 21ST BIRTHDAY

American power-hitter Frances Tiafoe celebrated his 21st birthday by reaching his first Grand Slam quarter-final, beating 20th seed Grigor Dimitrov 7-5 7-6(6) 6-7(1) 7-5.

"I told my parents 10 years ago that I was going to do this, I was going to change their lives and my life," said an emotional Tiafoe. "Now I'm in the quarters of a slam at 21. I can't believe it, man."

Inspiring words from Frances Tiafoe 🙏 pic.twitter.com/0MF0nysER8

— ITF (@ITF_Tennis) January 20, 2019

UNSEEDED COLLINS STUNS KERBER

Unseeded American Danielle Collins earned the biggest win of her career, beating second seed and 2016 champion Angelique Kerber 6-0 6-2 to reach her first Grand Slam quarter-final.

Giant Slayer 🙌

Having never won a match at a Grand Slam, Danielle Collins knocks out 2016 champion and 2nd seed Angelique Kerber 6-0 6-2 to reach the #AusOpen quarterfinals. pic.twitter.com/BScBVtz66j

— #AusOpen (@AustralianOpen) January 20, 2019

BARTY CONTINUES DREAM RUN

Australian number one Ashleigh Barty rode a wave of crowd support to edge former world number one Maria Sharapova 4-6 6-1 6-4 in Rod Laver Arena in a tense fourth-round clash.

Barty, bidding to become the first home winner of the Australian Open since Chris O'Neil in 1978, will face twice Wimbledon winner Petra Kvitova in her first Grand Slam quarter-final.

Massive performance from @ashbar96 who def. @MariaSharapova 4-6 6-1 6-4 in a thriller match and qualifies for her first Grand Slam quarterfinal!

Ashleigh Barty bat Maria Sharapova 4/6 6/1 6/4 et se qualifie pour son 1er 1/4 F en Grand Chelem. #AusOpen

📷 ©@corinnedubreuil / FFT pic.twitter.com/wxh9XuHjdh

— Roland-Garros (@rolandgarros) January 20, 2019

KVITOVA STORMS INTO QUARTERS

Eighth seed Petra Kvitova reached her first Australian Open quarter-final since 2012 after a commanding win over American youngster Amanda Anisimova.

The Czech struck 18 winners to win 6-2 6-1 in just 59 minutes.

She's back...

🇨🇿 @Petra_Kvitova is through to the QF's of a Grand Slam for the first time since the 2017 #USOpen after scoring a R4 win at the #AusOpen. Next up: 🇦🇺 Ashleigh Barty

📸: US Open pic.twitter.com/l20VlhnqeI

— US Open Tennis (@usopen) January 20, 2019