There is reason behind the way Rafael Nadal places his drink bottles at every match.

He plants the energy drink in front of the water bottle, both labels perfectly aligned and facing the court. It is the Spaniard's version of tennis feng shui.

Nadal's insistence on his bottle placement and refusal to step on the sidelines is a familiar act of "superstition" witnessed across tennis courts.

The iconic images of a bearded Bjorn Borg holding aloft the Wimbledon trophy - from 1976 to 1980 – reminds us of the Swede's strict no-shave rule at the tournament.

In his autobiography 'Open', American Andre Agassi disclosed that he wore no underwear in his only French Open triumph in 1999. The former world number one forgot to pack some for his opening match and decided to carry on without them.

While current world number one Novak Djokovic was quick to dismiss that he has any superstitions of his own, the Serb always eats the Centre Court grass after lifting the Wimbledon trophy and insists on bringing his two pet poodles to the tournament.

"I know that there are players who are going to the same shower all the time [in the locker room] because it's a superstition," Djokovic told Al Jazeera.

"I have rituals, like everybody. I think it's important. Humans are kind of a mechanism that work around the habits and a programme.

"Each day if you respect certain, I would say rituals, that you feel comfortable with, and if you get out of that comfort zone, sometimes it can cause a disturbance mentally."

Bjorn Borg employed a no-shave rule at Wimbledon [Getty Images]

Bouncing the ball a fixed number of times before serving, re-using the "lucky ball" the last point was won with, staying at the same hotel each year and eating a certain pre-match meal are some of the more common habits found on the professional tennis circuit.

From a sports psychology perspective, what appear to be trivial and, in some cases, nonsensical habits, in fact bring order to the chaos of sport.

"I see such things providing some consistency and sense of control,"  Dr Adam Naylor, Director of Telos Sport Psychology Coaching, told Al Jazeera.

"Superstitions are harmless for the most part but become harmful when they control the player rather than the player controlling them."

It would be tough to argue with the workings of a 21-time Grand Slam singles champion, but Serena Williams is reported to have a few bizarre habits.

The American wears the same pair of socks for a tournament run, always crosses the net from the opposite side of the umpire chair after the first game and brings her shower sandals to the court.

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She went as far as blaming her 2007 French Open quarter-final loss to Justine Henin on her failure to follow her set routine that day.

However, Naylor warned against tying superstitions to performance on court.

"If a player sees such things as necessary to their on-court success, these actions can be problematic for ultimate performance. If they are habits that give a player a good emotional vibe and a sense of being ready, they are beneficial."

Nadal did admit to Al Jazeera that his routines have no effect on his game, saying they were to "help with my focus".

The International Tennis Federation's 20-second limit between points is one of the most widely abused rule on the court.

Rafael Nadal's arrangement of his drink bottles is witnessed at every single match [Getty Images]

Players regularly stretch that to cater to their respective pre-point rituals.

The world's richest female athlete, Maria Sharapova, has made a career out of her deliberate routines. The Russian stands with her back to her opponents, stares at her strings while aligning them and clenches her fist before each point - like clockwork.

Nadal, who was regularly getting time violations for his prolonged pre-serve tics, now keeps one towel at both corners of the court, to speed up his drying routine.

"In tennis, routines between points allow the player to put the previous point behind them, relax and then get focused and energised for the point that lies ahead. That is crucial," Naylor added.

Such is the concentration and commitment of the players that after years of repetition, the rituals just become routine.

Superstitions become harmful when they control the player rather than the player controlling them

Dr Adam Naylor, Director of Telos Sport Psychology Coaching

Notorious for his 20-plus ball bounces before serving earlier in his career, Djokovic did not realise the distress he was causing opponents and fans.

"I wasn't even aware that I was bouncing the ball so much, especially at important moments," said the Serb.

From a record 38 bounces at a 2007 Davis Cup match against Australia, he averages five to seven now.

"Again, I worked mentally on myself to release that kind of pressure."

Superstitions are prevalent in tennis but not restricted to the sport. High-profile tennis players easily get exposed because of the individual nature of the game.

Naylor believes quirky, pre-game preparations and in-game superstitions are more evident in individual sports because they do not get lost in the shuffle of other team-mates.

"Only when the rituals are quite extreme are they noticeable in sports where athletes compete together, simultaneously," he said.

"The art of being a great athlete is accepting the feelings of stress competition produces and trusting that they can control enough elements of their game to produce a solid outcome."

Similarly, Nadal does not even think twice about placing those bottles or grabbing his shorts in practice.

It is the stress of competition that results in all the fidgeting, shirt-tugging and hair fixes.

Source: Al Jazeera