If it was not quite the way he would have wished to win his first grand slam title, when the enormity of his achievement begins to sink in Stanislas Wawrinka will not care one iota.

For so long in the shadow of his friend Roger Federer, Wawrinka gave Switzerland another grand slam champion yesterday as he beat an ailing Rafael Nadal 6-3, 6-2, 3-6, 6-3 to win the Australian Open.

Although world No.1 Nadal was severely restricted by a back injury, which hampered his movement and reduced his serve to a whimper for two sets, Wawrinka deserved his victory and planned to enjoy it. "There's a big chance I get drunk tonight," he said.

Today, Wawrinka will wake up not only as a grand slam winner but the world No.3, and Swiss No.1. Federer, who called Wawrinka to congratulate him last night, held that title for well over a decade.

Few people gave Wawrinka a chance, not least because he had failed to win a set in his 12 previous meetings with Nadal, who himself had looked so good and so strong in beating Federer in the semi-finals.

This was supposed to be grand slam win No.14 for Nadal, putting him level with Pete Sampras, who presented the trophy, and just three behind Federer, whose record of 17 was looking increasingly vulnerable.

But in beating the three-time defending champion Novak Djokovic in the quarter-finals, then Tomas Berdych in the semis, Wawrinka had shown he was in the form of his life, with a new-found mental strength to match his undoubted talent.

The 28-year-old won the title on merit and so well was he playing in the first set and at the start of the second, there is no saying that a fully fit, fully charged Nadal would have found a way to win.

Wawrinka's backhand, a thing of beauty, was a weapon of destruction, powering winners into the Spaniard's forehand corner, exploiting the space as he tried to run around his backhand.

It was an aggressive gameplan that paid dividends as he broke once to win the first set and again at the start of the second, before Nadal called for the trainer when trailing 2-1 and a break down.

He returned, to loud boos from the crowd who hastily hid their faces when they saw how badly injured Nadal was, especially on serve.

Lesser players, or those with less character, might have called it a day. Struggling, he asked his uncle and coach, Toni Nadal, in the stands, what he should do. "Play," came the response. "You don't quit in a final."

Toni Nadal probably thought the match was over and, with Nadal's serve so weak it barely registered on the speed gun, Wawrinka quickly wrapped up the second set.

But the nerves Wawrinka had done so well to suppress came out at the start of the third set, when he perhaps realised how close he was to the title. Playing an injured opponent is never easy and as Nadal improved, with the pain killers beginning to kick in, Wawrinka sprayed shots all over the place. Nadal duly took the set.

But under the guidance of his coach, Magnus Norman, Wawrinka now believes in his ability. At 4-2, he handed a service break back to a grateful Nadal but after breaking again he held serve superbly to clinch the biggest victory of his life.

The embrace between the two at the net was warm and lengthy, and only after Nadal slumped into his chair did Wawrinka truly celebrate.

"It's quite crazy what's happening right now," he said. "I never expected to win a grand slam. I never dreamt about that because for me, I was not good enough to beat those guys. To beat Rafa, even if he was injured, I think I played my best first set. I was ready to play four hours or five to beat Novak in the quarter, to beat Berdych in semis. That shows me I'm doing the right thing. If you practise well, work hard, you will always have a chance to be in a great position to play your best tennis."

In four of the past six years Nadal's Australian Open hopes have been struck by injury, including in 2013 when he could not play.

Now, he will look ahead to Paris, where he will bid for a ninth French Open title in June.

As usual, though, Nadal was classy in defeat, emphasising how well Wawrinka had played instead of cursing his luck.

"It's Stan's day, not my day," he said. "I tried my best and it was not possible today. I'm obviously disappointed and very sad. But that's life, that's sport. I really had a lot of great moments in my career. This is a tough one. Just accept and trying to keep working hard for what's coming."

It is an attitude that has served Nadal well throughout his career. Wawrinka may never get close to the Spaniard's tally of grand slams.

But he has one. And that is one more than he ever expected.