Australian Open: Djokovic strolls into semi after Nishikori retires

The world number one eased into a showdown with French 28th seed Lucas Pouille

djokovic-nishikori-reuters Novak Djokovic and Kei Nishikori shake hands with the chair umpire after the quarterfinal of the Australian Open in Melbourne | Reuters

Novak Djokovic was delighted to get back into the semifinals at the Australian Open after missing out for two years as Kei Nishikori retired injured on Wednesday.

The world number one eased into a showdown with French 28th seed Lucas Pouille as Nishikori retired after just 51 minutes when behind 6-1, 4-1 in the quarterfinal.

"Feels great. This has been my most successful Grand Slam throughout my career, the first one that I won back in 2008," said Djokovic, who is chasing a record seventh Melbourne Park title.

"I have a lot of beautiful memories from Rod Laver Arena.

"Yeah, past two years have been a bit tough with the elbow injury and everything. Over the past 10 years, I have had plenty of success here.

"Australia has been really kind to me throughout my career."

Eighth seed Nishikori had endured three five-set epics during 13hr 47min on court before the quarterfinal clash and suffered a thigh strain in the first set as his previous exertions took a toll.

After a medical timeout and three minutes of treatment from the physiotherapist, Nishikori emerged for the second set with his right thigh strapped and taped, and courageously attempted to carry on.

He seemed to be moving a little more freely, but the recovery did not last long.

After being broken to go 2-1 down by the Serbian 14-time Grand Slam champion Nishikori became almost immobilised.

When Djokovic broke again to go 4-1 ahead it proved the last straw for Nishikori's brave challenge.

"After third game or fourth game when I was serving, I felt pretty heavy to my right leg," Nishikori told reporters.

"After that I couldn't really bend my knees and couldn't jump up. Yeah, I decided to stop."

Djokovic wished his old foe Nishikori a speedy recovery after beating him for the 16th time in 18 meetings.

"I am really sorry to see him go through pain. He's had some tough injuries in the last couple of years. I am sure he's not feeling great about ending the Grand Slam this way," said the Serb.

"But he's had some marathon matches this tournament that probably have taken a toll on his body."

Djokovic was exhausted after his late-night four-set win over Daniil Medvedev on Monday and made no secret of his delight to escape the quarterfinal with such a light workout.

"As they say, this is exactly what the doctor ordered for me after the match two nights ago," Djokovic said.

"Not to spend too much time on the court.

"I have had plenty of matches so far this year and I am in another semifinal and I will do everything to get ready for that one."

Top seed Djokovic will now meet 28th seed Lucas Pouille on Friday after the Frenchman reached his first Grand Slam semifinal by ousting Milos Raonic in four sets.

Pouille became the first Frenchman to reach the semifinals of the Australian Open since Jo-Wilfried Tsonga in 2010 when he stunned Canada's 16th seed Raonic.

Pouille fought back from a break down in the first set to win 7-6 (7/4), 6-3, 6-7 (2/7), 6-4 and reach the last four of a Slam for the first time.

The 24-year-old had never won a match at Melbourne Park before this year. Pouille recently recruited 2006 Melbourne Park champion Amelie Mauresmo to his team after a splitting with long-time coach Emmanuel Planque in the off-season.

But the world number 31 came into Melbourne in poor form: he had lost all three of his singles matches at the Hopman Cup and suffered a first-round exit at the Sydney International.