Rafael Nadal and Novak Djokovic head to Wimbledon fearing the title may be beyond them as the season’s third grand slam tournament shapes up to be the most open in a decade.

World No.1 Nadal, fresh from a record ninth French Open title, was Wimbledon champion in 2008 and 2010 and runner-up in 2006, 2007 and 2010.

But his past two visits have been humiliating disasters.

The Spaniard suffered his first opening round exit at a grand slam in 2013 to Belgian journeyman Steve Darcis who was ranked 135 at the time and has not won a main tour match since.

Twelve months earlier, the world’s 100th best player, big-hitting Lukas Rosol put him out in the second round, a defeat which precipitated a seven-month absence from the sport for the man from Mallorca.

The 28-year-old hinted at another Wimbledon letdown in the immediate aftermath of his triumph over Djokovic in the French Open final two weeks ago where he claimed his 14th major.

“I am healthy, that’s the most important thing. I hope my knee will have a positive feeling on grass because I felt my knee was better last year on the other surfaces,” said Nadal, who has been seeded No.2 for Wimbledon.

Those feelings would not have been boosted by an opening exit on the grass at Halle last week, a straights sets loss to German world No.85, Dustin Brown.

World No.2 Djokovic, who won his only Wimbledon title in 2011 and was runner-up to Andy Murray in 2013, has not played a grasscourt warm-up event since 2010.

The 27-year-old Serb, the top seed for Wimbledon, won the last of his six majors at the Australian Open in 2013.

But his latest thwarted attempt to win a first French Open and become just the eighth man to complete a career grand slam represented his seventh defeat in 13 finals at the majors.

Even more worryingly, Djokovic has now lost five of his last six grand slam finals.

The coaching role of three-time Wimbledon champion Boris Becker has never looked so crucial.

Meanwhile, defending champion Murray goes into the tournament with his form also giving cause for concern.

The world No.5, who recently hired Amelie Mauresmo as coach, hasn’t reached another final since and lost in the third round at Queen’s Club last week to 35-year-old Czech, Radek Stepanek.

Murray has been seeded three for Wimbledon, above seven-time champion Roger Federer who may have most reasons for being confident about an eighth title having captured the Halle grasscourt trophy for the seventh time at the weekend.

The 32-year-old, who won the last of his 17 majors at Wimbledon in 2012, hopes his success in Germany is a sign of good things to come in south-west London.

“In the past, when I have played well at Halle I have usually played well at Wimbledon,” said the Swiss star.

Last year, Federer was knocked out in the second round by Ukraine’s world No.116, Sergei Stakhovsky, ending his run of 36 straight grand slam quarter-finals.

Should he triumph in London Federer would succeed Arthur Ashe as the oldest men’s champion and break free of his seven-title tie with Pete Sampras.