Daniil Medvedev has beaten Rafael Nadal for the first time ever in what was another three-set semi-final classic at the ATP Finals.

We have been denied a Djokovic v. Nadal showdown because of two extraordinary talents.

Rafa Nadal has never won the ATP Finals and the curious wait continues after an inspired Daniil Medvedev defeated the 20-time grand slam champion on Saturday night at the O2 Arena in London.

Nadal served for the match at 5-4 in the second set but was broken to love before Medvedev secured the crucial break midway through the final set to set up the last final of this event to be staged at the O2 before it moves to Turin after 12 years in England's capital.

The result means that Medvedev reaches his maiden ATP Finals decider where he will face the current US Open champion and last year's beaten finalist, Dominic Thiem, who overcame Novak Djokovic earlier on Saturday in the first titanic battle of the day. No matter what now, we will have a new champion.

Medvedev came through against Nadal in over two hours, 3-6, 7-6 (4), 6-3. For the first time in over 70 matches, when Nick Kyrgios beat him in February 2019 at the Mexican Open in Acapulco, Nadal has lost a match after winning the first set, and Medvedev was full value for his impressive victory.

Daniil Medvedev of Russia smiles after winning against Rafael Nadal of Spain in their semifinal match at the ATP World Finals tennis tournament at the O2 arena in London, Saturday, Nov. 21, 2020. (AP Photo/Frank Augstein)

Nadal had won all three prior meetings between the pair, including a three-set victory in the group stages of last year's ATP Finals and at the US Open final two months earlier, where Nadal prevailed in five sets.

Medvedev finished 0-3 from his three group matches on his ATP Finals debut 12 months ago but completely turned the tables around this year. He arrived at the event in flying form having just won the Paris Masters - also an indoor hardcourt tournament.

The Russian bested Alexander Zverev, Djokovic and Diego Schwartzman, all in straights sets, en route to his semi-final clash with Nadal.

Meanwhile, Nadal, who failed to advance to the last four last year, started this tournament with a routine dispatching of ATP Finals debutant Andrey Rublev (winner of the most ATP titles in 2020 with five in total) and beat the 2019 champion, Stefanos Tsitpisas, in a winner-takes-all contest after Nadal had lost to Thiem in two close sets.

First win over Nadal, first final in London 👏@DaniilMedwed completes an incredible 3-6, 7-6(4), 6-3 comeback!#NittoATPFinals pic.twitter.com/GgT5wPLAeL

— ATP Tour (@atptour) November 21, 2020

This was a difficult night for Nadal and he was never truly comfortable, despite coming bizarrely close to winning the contest in straight sets. By the midway point of the first set, Nadal's service games were averaging around six and a half minutes in length compared to Medvedev's 90 seconds or so.

The 13-time French Open champion was getting just 40% of his first set first serves in; a figure which only marginally improved to 52% in the second set. By Nadal's standards, these were poor statistics and especially so when measuring Medvedev's 77% first serve accuracy. Medvedev raced into a 4-1 second-set lead, hitting 12 winners to Nadal's zero and six aces to one.

By the start of the third set, Medvedev had struck twice the number of total winners and made just three more unforced errors than Nadal, suggesting that Medvedev's aggressive, brave play was additionally accurate. And yet, for two-thirds of this engrossing battle, it appeared as though Goliath would predictably triumph.

As peerless as Nadal is on clay, indoor hardcourt is easily his worst surface. He has won just a solitary indoor hardcourt tournament - way back in the mid-2000s - and has only reached two finals at the ATP Finals despite qualifying for the prestigious event 16 years in a row.

In 2010, Nadal lost the final in three sets to Roger Federer and was beaten three years later on the same stage, this time in straights sets by Djokovic. Against Medvedev on Saturday, it looked like Nadal would finally correct that strangely substandard record.

He won the first set 6-3 having spent the majority of it fighting desperately to hold serve. Then out of the blue at 4-3, Nadal broke Medvedev to love and served out the set. The result looked like a foregone conclusion considering the duo's head-to-head record and the fact that it had been almost two years since Nadal lost a match after winning the opening set.

However, this was no ordinary occasion. Medvedev was defiant without distraction and immediately broke Nadal in the second before racing into a 4-1 lead, spurning a break point which would have made it 5-1 to the Moscow man.

But the 24-year-old did not take this opportunity and he felt the repercussions shortly thereafter.

Nadal held and then broke Medvedev with some incredible passing shots and that world-famous determination of his which has made him the joint-most successful men's player in history.

Like in the first set, Nadal suddenly served for this one at 5-4. He was nailed on for his first final here in seven years until Medvedev broke him to love with some outrageous shot-making of his own.

At 3-3 in the deciding set, the match took its fatal turn for Nadal when at the third time of asking, Medvedev broke his serve followed by his will to complete one of the greatest victories of his career just days after beating Djokovic.

So, at around 6pm on Sunday, Medvedev will face Thiem in the last ATP Finals match to be held at the O2 Arena in London, where a first-time champion will be crowned.

Whoever wins, the new name on the trophy will be a justified one as the Big Three, at last, get some long overdue and worthy competition to challenge their dominance.

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