Spain’s Rafael Nadal fought off tenacious Argentine Diego Schwartzman to win through to the quarter-finals of the Australian Open on Sunday, ensuring he remains world number one after the tournament ends.

Nadal was taken to four gruelling sets in almost four hours before winning 6-3, 6-7 (4/7), 6-3, 6-3 on Rod Laver Arena.

It will be his 10th Australian Open quarter-final appearance, second only to Roger Federer, and he will face Croatia’s sixth seed Marin Cilic. Nadal leads 5-1 in their previous meetings.

It was the Spaniard’s fourth win over the Argentine but his toughest after beating him in straight sets in the second round at the 2015 US Open.

By winning Nadal ensured that he will remain No.1 when the new rankings are released the day after the Open ends.

“Of course, I feel little bit tired, but yeah good. I was able to keep fighting until the end,” he said.

“It is the first big match I played in 2018. I started later than usual so a match like this probably helps because you know that helps confidence in myself.

“That’s confidence knowing that I can resist almost four hours on court playing at a good intensity.”

Nadal broke in the eighth game on the way to taking the opening set, but he encountered stiff resistance in the second set. There was six service breaks as Nadal could not shake off the tigerish Argentine, who levelled the match by winning the tiebreaker when the top seed’s forehand was long.

There was a magical moment when Schwartzman ran down a drop shot and won the point with an angled volley across the net to break back at 4-4.

Nadal took control in the third set with a break in the fourth game, but he had to fight off five break points before holding serve in a titanic 13-minute second game in the final set.

He broke in the third game of the fourth set, but had to make some monumental holds of service to keep Schwartzman at bay, winning on his third match point with a return winner.

Dimitrov ousts Kyrgios

Bulgaria’s world No.3 Grigor Dimitrov won a gripping four-setter to knock Australia’s big hope Nick Kyrgios out of the Australian Open on Sunday.

Dimitrov downed the 17th seeded Kyrgios 7-6 (7/3), 7-6 (7/4), 4-6, 7-6 (7/4) in 3hr 26min and will face Britain’s Kyle Edmund in the quarter-finals on Tuesday.

Dimitrov stepped up his campaign after a couple of indifferent wins in the earlier rounds to avenge his defeat to Kyrgios in the semi-finals of this month’s Brisbane International.

He won all three tiebreakers in a charged night match atmosphere on Rod Laver Arena before a capacity home crowd willing their player on.

“Playing against Nick is always tricky, two weeks I lost against him,” Dimitrov said.

“He was serving and playing unbelievable and he fought really hard. It’s one of those matches that you have to be locked in and try to get any opportunity you have.

“Even when I was serving for the match I felt that I was not finding my spots very well and I’m just glad I got through that match.”

Edmund makes first quarters

British hope Kyle Edmund reached his first Grand Slam quarter-final with a four-set win over Italy’s Andreas Seppi.

The unseeded Edmund, ranked 49, lost the opening set, but finished strongly to win 6-7 (4/7), 7-5, 6-2, 6-3. In the process, he became the first British man other than Andy Murray to reach the quarterfinals at the Australian Open in 38 years. He will face Nick Kyrgios or Grigor Dimitrov in the last eight

Cilic overcomes Carreno Busta for 100th Slam win

Croatia’s Marin Cilic won his 100th Grand Slam match as he mastered Spain’s Pablo Carreno Busta in four sets to reach the quarter-finals of the Australian Open on Sunday.

The former US Open champion won the big points in putting away the 10th seed 6-7 (2/7), 6-3, 7-6 (7/0), 7-6 (7/3) in 3hr 27min on Margaret Court Arena.

He will face either world No.1 Rafael Nadal or Argentina’s Diego Schwartzman in the quarters on Tuesday.

Cilic reached the last eight in Melbourne for the second time and also claimed his 11th Slam quarter-final to equal Goran Ivanisevic’s record for appearances at that stage of the majors by a Croatian man.

The Croat won two of the three tiebreak sets and was superior to Carreno Busta in the pressure moments of the round of 16 match.

“There were lots of ups and downs and Pablo gave me a lot of trouble in that third set where he was twice a break up and it was difficult mentally,” Cilic said.

“We had a lot of tough rallies in difficult humid conditions so I was really glad how I stayed in there mentally and really played well in the end.”

Cilic served 20 aces, broke serve six times and made a total of 73 winners as well as winning the majority of the long rallies.

“That’s my style of play. Pablo is extremely solid from the back of the court and has great shots both on the forehand and backhand and he was serving really good today,” Cilic said.

“It was a big battle and I am really relieved that I played such a great tiebreaker at the end.”

Cilic said he faced a big challenge against either Nadal or Schwartzman in the quarter-finals.

“I have played great tennis from the first round against tough opponents and now I am really looking to the next match, it will be definitely be a big challenge,” he said.

Carreno Busta reached the semi-finals of last year’s US Open where he lost to Kevin Anderson and also made the quarter-finals at Roland Garros in the same year.

He was bidding to reach the quarter-finals in Melbourne for the first time.