There have been plenty of iconic Serena Williams moments over the years, but do you remember the time she ordered a coffee during the middle of a match? Back in 2015, the former world number one was competing against Flavia Pennetta in the Hopman Cup, when she suddenly felt the need for a caffeine fix. Williams had lost the first set 6-0 and clearly thought that an espresso shot would give her the boost of energy needed to turn things around. 

Did Williams actually get a coffee? 

Before the start of the second set, the American turned to the umpire and asked: “Is it illegal to order an espresso?” 

Evidently, this was not something the chair umpire was used to answering but after it was established that drinking coffee was not against the rules, Williams was quickly brought the espresso she craved. 

Remarkably, the coffee had the desired effect and Williams went on to win the next two sets 6-3 6-0. 

Speaking afterwards, the 23-time time Grand Slam winner explained that she’d been suffering from jetlag during the match, having arrived in Australia less than 48 hours before her match against Pennetta. 

WATCH: Williams orders espresso on court

"I am a coffee drinker and I didn't have mine this morning and I was just feeling it," she revealed.

 "So I had to get some coffee in me.

"I told them to just give me a shot of espresso. I asked them if it was legal - 'Is it illegal to have a shot of espresso?' - because I had never done it before.

"I needed some espresso. I needed to wake up - the jetlag gets you all the time."

Zhang Shuai eats sandwich on court

While Williams’ coffee drinking heroics will live long in the memory, Chinese star Zhang Shuai took things to the next level at the Japan Open on Tuesday when she started eating a sandwich. 

Zhang was playing France’s Caroline Garcia in the second round and and tucked into her snack at the end of the second set. 

The 33-year-old went on to win the match and book her place in the quarter-finals. 

WATCH: Zhang Shuai eats sandwich on court

Will Williams return to tennis?

Though Williams’ playing days are over, she has hinted that she has not completely closed the door on a tennis return. 

However, for the time being, the American is focused on things that tennis had previously prevented her from doing.

Speaking on the Tonight Show with Jimmy Fallon, she stated: “There are so many things that I’ve been wanting to do for so many years and I’ve had such a passion for tennis for so long that I’ve never done them. 

“Now it’s time for me to start to enjoy those things.”