It is the debate that pollutes a thousand friendships: is Roger Federer, who has won 17 majors, entitled to be regarded as the greatest player tennis has ever seen if he has lost 23 times in 34 matches to Rafael Nadal, who has won 14 slams? At Rod Laver Arena here on Sunday , we will have more evidence to pore over when they contest the final of a grand slam tournament for the 12th time.

This is the final no one expected but nearly everyone wanted. A fortnight ago, nobody outside their immediate circles would have predicted that the title would be decided between the world No17 and the world No9 in a stretch of competition where Andy Murray and Novak Djokovic are so far ahead of the field that their nearest rival is Milos Raonic, the ailing Canadian who went out to Nadal in the quarter-finals.

Nadal, who turns 31 during the French Open, and Federer, who will be 36 in August, are revisiting their rivalry partly because Denis Istomin, ranked 117 in the world, made the Spaniard’s job easier by eliminating Djokovic in the second round, then Mischa Zverev (ranked 50) shocked Murray in the fourth round on the other side of the draw. Those upstarts lost their next matches, but they had left their mark on the tournament in dramatic style.

The old campaigners, meanwhile, worked their way through the draw with varying degrees of sweat and panache, Nadal surviving the most searching examination in the semi-finals when he took nearly five hours to beat the superb Grigor Dimitrov on Friday night. Federer’s semi-final against Stan Wawrinka also went five sets, but lasted about two hours less and was played a day earlier.

Both were understandably tired by their efforts and, unusually, decided not to talk to the media on the day before the final. There was, though, one expert voice to provide perspective.

Dimitrov, so similar in style to Federer (and a client of his agency, Team8), left the tournament a revivified presence on the Tour because he pushed Nadal so hard and the result was in doubt all the way to the final point.

“He’s such a fighter, such a competitor,” the world No 15 said. “It was an honour for me to play a match like that against him. It also shows me that I’m in a good way, I’m on the right path. One thing I can say is that I left it all out on the court. It’s been super intense. He really shows why he’s [still] Rafa.”

That could be a determining factor in the final because Nadal also had to give every last drop of sweat to get past him. He said he was exhausted, which was self-evident by his demeanour and his eagerness to leave the site and get some sleep.

Roger Federer: in numbers 1 – the last time he was ranked world No1 was 29 October 2012, with the first time being in February 2004

4 – the number of times he has lifted the trophy in Australia; the years were 2004, 2006, 2007 and 2010 17 – his number of grand slam titles, which is also the all-time record 28 – his number of grand slam final appearances 63 – his first-serve percentage in this year's tournament before the final

$98,830,825 – prize money he has earned during his career, singles and doubles combined

A lot of the elite players want no more to do with a tournament when they lose. They are just keen to get out of town and regroup. When Djokovic lost to Marin Cilic in the Paris Masters in November, he was asked if he would stay on to watch Murray as he bid to overtake him as world No1, he replied: “I’m planning definitely to stay another few days here with accreditation and watch all of his matches, yes ... and leave my son at home.”

Dimitrov reacted differently. As disappointed as he was about falling just short, he said: “I’m going to watch it for sure. It’s super amazing. It’s great for the sport again.”

So it is. For all that the game could do with some of the younger players breaking through to challenge Murray and Djokovic, there is an audience out there that relishes the return of Federer and Nadal. Theirs has been the rolling war that defined the first decade of the millennium. It seemed at one point it would last until they chose it not to.

That was unrealistic. As great as they are, they are prisoners of time like all the others. But they have a chance here to remind us what we have been missing.

If the groin strain Federer picked up against Wawrinka has eased sufficiently to allow him to move like he did when destroying Tomas Berdych, he could win it in four sets; if Nadal can carry the sheer animal grit he displayed against Dimitrov over the course of five sets, he should be too strong for his old friend. I suspect the latter will be the case.

Previous finals

French Open, 2006, Nadal A 20-year-old Nadal became the first man to defeat Federer in a Grand Slam final. Federer dropped one set leading up to the final, while the Spaniard dropped two. Nadal won the match 1-6, 6-1, 6-4, 7-6 (7-4) to retain the title.

Wimbledon, 2006, Federer The Swiss quickly took revenge, with the world No1 winning in four sets, 6-0, 7-6 (7-5), 6-7 (2-7), 6-3.

French Open, 2007, Nadal Nadal denied Federer the hope of completing the set of Grand Slam titles as he won a third consecutive French Open, prevailing in four sets, 6-3, 4-6, 6-3, 6-4.

Wimbledon, 2007, Federer History repeated itself as Federer again gained revenge for his French Open final defeat, winning 7-6 (9-7), 4-6, 7-6 (7‑3), 2-6, 6-2.

French Open, 2008, Nadal Nadal thrashed the world No1 6-1, 6-3, 6-0 to become the seventh man to win a Grand Slam title without dropping a single set.

Wimbledon, 2008, Nadal Federer had won the competition five years running but Nadal won his first Wimbledon title 6-4, 6-4, 6-7 (5-7), 6-7 (8-10), 9-7 in a thrilling four-hour 48-minute contest.

Australian Open, 2009, Nadal Nadal took his tally to five Grand Slam final victories over Federer as he won his first Australian Open 7-5, 3-6, 7-6 (7-3), 3-6, 6-2.

French Open, 2011, Federer Federer ended Novak Djokovic’s 43-match unbeaten run in the semi-final, but he lost the final 7-5, 7-6 (7-3), 5-7, 6-1.