The behaviour of Australian Open crowds was thrust into the spotlight yet again on Tuesday night as Matteo Berrettini created tennis history by reaching the semifinals at Melbourne Park with a rollercoaster five-set victory over Gael Monfils. 

The seventh seed overcame the French 17th seed in their quarter-final 6-4 6-4 3-6 3-6 6-2 to become the first Italian man to reach the last four of the Australian Open. 

Berrettini, a Wimbledon finalist last year, will now face 20-time Grand Slam champion Rafael Nadal on Friday for a place in Sunday's final. 

"It feels unbelievable (to be the first Italian), hopefully there will be a second one tomorrow with Jannik Sinner," Berrettini said of his compatriot, who faces Stefanos Tsitsipas in a quarter-final on Wednesday. 

"I was really happy with myself, it was a great fight with Gael, a great match, a lot of emotions. 

"I thought I had him in the third set but then I found myself in the fifth. I really fought hard and I put everything into the court." 

There's been debate over whether boisterous crowds in Melbourne have helped create an awesome atmosphere or crossed the line. Some thought it was the latter during Nick Kyrgios and Thanasi Kokkinakis' thrilling doubles quarter-final win on Tuesday while the hometown heroes have called for more of the same in their next match. 

Russian favourite Daniil Medvedev also took aim the "low IQ" crowd after his second-round win over Kyrgios. 

As Berrettini conducted his post-match on-court interview with ex-Aussie tennis star Sam Groth, he was interrupted by a heckler who yelled out from the stands. 

It was not completely clear what was said, but part of the heckle sounded like "f*** you". 

The Italian stopped and looked over at where the noise came from, clearly unimpressed, as other fans booed the culprit. 

"I didn't hear," Berrettini said. "It's full of people and I like it — some of them are not really tennis fans I think." 

That clip earned the Italian a fresh round of applause from tennis lovers who appreciated the five-set thriller they'd been treated to. 

"It is what it is, you know. You cannot control everybody," he added. "I think to be respectful is something that you have to do anyway but it's fine, I win, I'm happy." 

Early in the fifth set umpire James Keothavong had heard enough from unruly spectators as they made noise while Monfils was trying to serve. 

"If you don't want to watch, please leave," he said. Fans cheered the official and then boos erupted as play was halted while security spoke to the section of the crowd responsible for taking things too far. 

In a grinding three hour and 49-minute match on Rod Laver Arena, 25-year-old Berrettini grabbed a double break to surge clear in the fifth set after Monfils had roared back from two sets down. 

It was Berrettini's sixth win in seven career five-set battles. There were many drawn-out, attritional games, including a monumental 20-minute Berrettini service hold game of 10 deuces to give him the edge in the 62-minute second set. 

It means the 35-year-old Monfils, who won the warm-up Adelaide tournament and had not dropped a set in his previous four matches, came up just short again in his first quarter-final appearance in Melbourne since 2016 when he lost in four sets to Canada's Milos Raonic. 

Monfils credits his recent resurgence to the stabilising influence of his new wife, women's world number 17 Elina Svitolina. The tennis "power couple" tied the knot in Geneva in July just before the Tokyo Olympics.