Here are four things we learned from the first Masters 1000 of the year on clay:

1. Nadal still untouchable

Watching the world No.1 dominate on the red dirt has become a familiar sight over the last 13 years, but his lack of match action prior to his favourite part of the season indicated he might be susceptible to defeat.

Nadal’s performances in Monte-Carlo emphatically dispelled suggestions his aura on the most physically demanding surface of all had diminished. He romped to an 11th title without conceding a set and the gulf in quality between him and the rest remains considerable.

Can anyone stop the ‘King of Clay’ winning Roland Garros on June 10? No, is the only plausible response.

Nadal’s most dangerous opponent in the months ahead may be his own body. If he remains fit and avoids injury, the clay-court season will end with the sound of the Spanish national anthem echoing around Court Philippe Chatrier.

2. Time for optimism

Novak Djokovic’s curious fall from grace has garnered significant attention, but there are finally signs that his time in the wilderness may be coming to an end.

Despite a third round defeat to Dominic Thiem in Monaco, the former world No.1 performed with the sort of intensity and drive that was synonymous with his success.

His decision to reunite with Marian Vajda, after an 11-month separation, will prove to be a canny move. A familiar face, who will demand high standards are met without fear of reprisal, is exactly what the Serbian requires as he plots his route back to the top.

Djokovic did not have much luck with his draw in Monaco – and the pattern has continued in Barcelona. He could encounter Nadal in a blockbuster last eight clash later this week.

3. Nishikori’s back on the scene

Nishikori was forced to end his 2017 season prematurely due to a wrist problem – but his departure from the Tour slipped under the radar.

The Japanese, who is no longer the No.1 player from Asia, announced his injury news around the same time Andy Murray, Stan Wawrinka and Djokovic highlighted their own fitness woes.

It’s been a difficult spell for the former world No.4, and his shotmaking skills have been missed in the latter stages of tournaments. His run to the final in Monte Carlo was unexpected but welcome, and he remains a joy to watch with the red dirt beneath his shoes.

If, and it’s a big if, Nishikori can remain fit, he could bank some much-needed ranking points in the weeks ahead. He came within a whisker of glory at the Madrid Masters in 2014, and he should be targeting success in the Spanish capital next month.

4. Dimitrov’s slump is over

Grigor Dimitrov endured a torrid March, which included early exits in both Indian Wells and Miami.

Prior to his involvement at his hometown tournament on the Côte d'Azur, the Bulgarian had lost four of his five previous matches. He appeared bereft of confidence, but a change in surface has revitalised his floundering season.

Clay is never going to be Dimitrov’s strongest suit, but a last four appearance in Monaco offers him encouragement for the challenges ahead. Ultimately his aim, though, should be to find a level of consistency before tackling the grass-court swing with optimism.

Despite his productive week in the principality, Dimitrov’s second serve remains an area of concern. He has won a lowly 48% points behind his second delivery this season, which is down 4% on last year – a considerable drop.