The key to the longevity of Novak Djokovic and Roger Federer is their willingness to constantly “listen, learn and improve every single day”, says the Serb’s coach Goran Ivanisevic.
Djokovic, 32, and Switzerland’s Federer meet for the 50th time in Thursday’s Australian Open semi-final.
Federer, 38, has not beaten Djokovic at a Grand Slam since 2012.
“Sometimes you think why the heck do you want to learn more? That’s why they – and Rafael Nadal – are the best,” Ivanisevic told BBC Radio 5 Live.
Defending champion Djokovic is going for a record-extending eighth title at Melbourne Park, while Federer is aiming to match his opponent’s current tally with a seventh victory.
Djokovic, ranked second in the world, won their most recent meeting at a Grand Slam in an enthralling Wimbledon final last July, which concluded with that historic final-set tie-break.
World number three Federer, however, did beat him over three sets at the ATP Finals in November.
The other interesting sub-plot to their Melbourne semi-final is the continuing race between the pair – and Spain’s Nadal – to finish with the most Grand Slam titles.
Federer leads the way with 20 majors, one ahead of current French Open and US Open champion Nadal and four clear of Djokovic, who won the Australian Open and Wimbledon last year.
“These guys are pushing each other,” added Croatian Ivanisevic, who won Wimbledon in 2001.
“They still want to improve every day – that’s the difference between the three of them and the young guys.
“They are not afraid to ask, listen and learn.”
Australian Open: Federer saves seven match points to beat Sandgren
What they say about each other
Djokovic on Federer: “He is one of the all-time greats and the match-ups against Roger and Rafa have made me the player I am today.
“You know he’s always going to play at such a high level, regardless of the surface.”
Federer on Djokovic: “Novak also has gone on all these runs like I did for 10 years. He did the same for the last 10 years.
“I think conditions suit us well here. Start the year strong. Probably something to do with court speed, feeling comfortable down here.
“It helps when you start the year off with a bang like he did at the ATP Cup.”
Why Djokovic loves Melbourne Park
Djokovic claimed sole ownership of the record for the most Australian Open men’s titles, moving clear of Federer and Australian great Roy Emerson, when he swept aside Nadal in the final 12 months ago.
On a court where he has produced some of the finest performances of his career, he has continued to show this year why he is widely considered as the man to beat.
Djokovic has not dropped a set since his opening match against big-hitting German Jan-Lennard Struff, losing serve just once in the past four rounds.
Will Federer be fully fit?
With Federer well into the twilight of his career, he has to carefully manage his workload to preserve his body for the things that matter most: the Grand Slams.
And that appears to have worked in his favour at Melbourne Park, having come through some long matches.
He has also been helped by a favourable draw as all five of his matches have been against unseeded players.
However, they did not all prove straightforward.
Only a fightback from 8-4 down in the 10-point deciding-set tie-break against Australian John Millman stopped him falling in the third round.
In the next round he was pushed by Hungary’s Marton Fucsovics before winning in four.
Then, he saved seven match points – and overcame a groin problem – to beat American Tennys Sandgren.
After the match Federer played down concerns he would not be fit enough to face Djokovic.
“I don’t know if you can call it an injury. It’s just pain and problems. I need to figure it out,” he said on Tuesday.
“You have an extra day, adrenaline, there are a lot of things [to help]. Two good nights of sleep, doctors, physios.
“Hopefully we’ll find out that it’s actually nothing bad.”
The race to be the ‘GOAT’
Djokovic’s victory over Federer in the Wimbledon final took him closer than ever to the Swiss’ Grand Slam tally.
Now the Serb, who has won six of the past nine tournaments in Melbourne, is aiming to further reduce the gap.
Almost six years younger than Federer, Djokovic will have the chance to add several more – barring a dramatic loss of form or injury problems.
His pursuit of Federer and Nadal is made more remarkable by the fact he won his first major in 2008 – when Federer had claimed 13 and Nadal five – and only added a second three years later.
On Thursday, he has the opportunity to take a huge step towards reducing the gap to three – it just so happens the man standing in his way is the man he is ultimately chasing.