Serena Williams has called out a "double standard" in tennis following the repercussions of Alexander Zverev's vicious outburst at the Mexican Open.

The world number three smashed his racquet against the umpire's chair after he and doubles partner Marcelo Melo lost to Lloyd Glasspool and Harri Heliovaara in Acapulco.

Zverev and Melo were trailing 8-6 in the tie-breaker when a close decision went against them, to which the German initially verbally exploded at umpire Alessandro Germani and called him a "f***ing idiot."

After the defeat, Zverev shook hands with his opponents and then aggressively struck the umpire's chair three times as he walked past.

He was inches away from Germani, who had to lift his feet up to avoid being hit.

Zverev struck the chair one more time after shouting: "You destroyed the whole f***ing match."

The 24-year-old was fined £30,000, forced to forfeit his prize money, and was kicked out of the tournament in which he is the defending singles champion.

However, despite the action taken against him, Williams believes if she had been in Zverev's position, the punishment would have been a lot worse.

"There is absolutely a double standard," the 23-time Grand Slam champion told CNN. "I would probably be in jail if I did that — like, literally, no joke.

"You see that [double standard] when you see other things happening on the tour, like, 'wait — if I had done that?' Hmm.

"But it is okay. At the end of the day, I am who I am, and I love who I am."

In 2009, Williams was placed on a two-year probation and fined $175,000 (£132,000) for 'major offence of aggravated behaviour' in the US Open semi-final against Kim Clijsters.

Williams clashed with a line judge after being called for a foot fault during a serve.

The infamous 2018 US Open final also saw Williams sanctioned. The US star was deemed to have been receiving instructions from her coach, to which she defended herself, stressing she does not cheat during matches.

Tensions escalated between Williams and umpire Carlos Ramos, however. After receiving a formal warning for the interaction between her and coach Patrick Mouratoglou, Williams was then given a point deduction after smashing her racquet against the ground in frustration.

Ramos then issued a third code violation — a game penalty to Williams for verbal abuse after the two had engaged in an ongoing exchanging of words.

Former world number one Mats Wilander has also called out the treatment of Zverev and believes the German has got off lightly.

"If a player breaks his racquet on the umpire's chair and he is literally a few centimetres away from hitting the umpire's leg, he should not be allowed to get on a tennis court until he has gone through some kind of rehab, some kind of time," Wilander told Eurosport.

"We need to punish him accordingly, and allowing him to come out and play professional tennis the week after or two weeks after, that is too soon."