Since his recovery, after a long interruption due to a knee injury, Rafa Nadal's results are exceptional: eight tournaments, eight finals, six titles.

And yet he is not satisfied. Of course, Nadal is aware of the exceptional character of his results, but concerning the level of his game and the situation with his knee, he still has certain concerns.

That is, in any case, what he declared shortly after his success in Barcelona. For those who had seen his performance in Monte Carlo against Novak Djokovic, one could only agree with him about the quality of tennis produced - which was insufficient

Novak Djokovic made a wonderful impression when beating Rafael Nadal in the final of the Monte Carlo Masters.

I had the pleasure of watching a player who was entirely confident and relaxed, who thrived on the pressure of facing Nadal.

Even if Rafa is a huge fighter and pushed the Serb to a tie-break in the second set, I never felt at any moment that the Mallorcan had control over his destiny. Djokovic dominated the conversation.

Rafa has suffered a number of damaging defeats inflicted by Djokovic since 2011. For two years he has been hurt by Djokovic's remarkable resilience and has developed a

It’s a source of great happiness to see Rafael Nadal returning to top-level tennis.

Even his rivals were talking about the vacuum he left behind when he took several months off with a knee injury. The tennis world missed him – probably as much as he missed tennis.

And the results are very encouraging. He reached the final of Vina del Mar in his first tournament, then won in Sao Paulo, and again in Acapulco, thrashing world number four David Ferrer in the final.

If the opponents in the first two tournaments were modest, then his foes in Mexico – Ferrer and Nicolas Almagro – were anything but.

For the first time in a while, 2012 saw the Grand Slams shared out amongst four different players. From 2004 to 2010, they were almost entirely dominated by just two – Roger Federer and Rafa Nadal, before Novak Djokovic came through in 2011. 2012 felt like a crossroads.

Where does the sport go now? It looks as if tennis will be ruled by two men again – but this time it’s Djokovic and Andy Murray. It is that duo who have etched their name on the last three major tournaments (Murray winning the Olympic Games and the US Open, Djokovic triumphing in Melbourne). It’s those two who have stolen a

David Ferrer of Spain (AFP)

The Big Four is stronger than ever with Andy Murray finally now having elevated himself alongside the other three. But who can upset the established order? Here are a few thoughts.

Is there anyone capable of upsetting the Big Four?

David Ferrer enjoyed a remarkable year in 2012, but still failed to win any big matches at the Major tournaments. The only players still active outside the Big Four who have managed to reach or win a Grand Slam final in recent years are Jo-Wilfried Tsonga, Juan Martin Del Potro and Tomas Berdych.

Frenchman Tsonga is attempting to re-structure his game after having

Andy Murray (Reuters)

The past 12 months have delivered their fair share of changes on the ATP circuit.

Novak Djokovic may well have been able to retain his status as undisputed world number one, but Andy Murray finally managed to make his mark at the highest level by winning Olympic gold and claiming his first Grand Slam title at the US Open.

Rafael Nadal was forced to miss the entire second half of the season and, while Roger Federer enjoyed a great year, the Swiss and the Majorcan have been forced to accept Djokovic and Murray as genuine rivals.

Now the expression 'Big Four' - previously a questionable term,

Novak Djokovic (Reuters)

Novak Djokovic ended the year as world number one and that in itself is a great achievement.

This year, there was no one player who was able to dominate the circuit as Djokovic did in 2011. All four Grand Slam titles were shared by different players. And the battle for world number one status raged between the Serb and Roger Federer right until the end.

Djokovic was far less dominant than he had been in 2011, but he still managed to bounce back from the period following the Australian Open, when he couldn't seem to string victories together.

The end of the first part of the year was very