Novak Djokovic has had a tumultuous start to his 2018 and was dealt a challenging opening round battle with Japanese tennis superstar Kei Nishikori at the Madrid Open on Monday afternoon.In the middle of a tightly contested second set, Novak’s current struggles were epitomised by one of the worst shots you might ever see him hit.The mishap came in the second set with the two competitors having shared three games apiece.Having been put on the back foot, Nishikori had failed to get enough distance on an attempted lob from the back of the court.Perhaps with too much time to think about it, however, Djokovic was unable to put away what looked a relatively simple overhead smash.As you can see below, it will be one of those the Serb will have nightmares about for the next few days.

You would have bet your house on Novak putting that one away. Nishikori had given up on the point before the smash was even being lined up.

The shot perfectly symbolised the kind of struggles Djokovic has been facing at the start of his 2018 season. Following an injury-laden last 14 months, the former world number one has struggled to rediscover the form that made him so dominant just a few years ago.

The Joker has been eliminated before the quarter-finals of five tournaments already this year and also bowed out early in his last outing at the Monte Carlo Masters, after being defeated by Dominic Thiem in the third round.

These stuttering performances led to him parting company with coaches Andre Agassi and Radek Stepanek back in April and bringing back Marian Vajda and Gritsch.

With such a bumpy start to 2018, many fans were eager to see his first-round matchup with the explosive Nishikori. Thankfully for the Joker, he managed to shake off the errant lob and claim a hard-fought straight sets victory 7-5 6-4.