John McEnroe has warned Novak Djokovic he will have to face up to being the "bad guy" for the rest of his career after the world No.1 was defaulted from the US Open for striking a ball which hit a line judge.
On Monday, the total financial penalty for Djokovic's disqualification was increased to $267,500 ($A370,000).
Djokovic was docked an additional $7,500 ($A10,000) for skipping the mandatory post-match news conference after being defaulted in the fourth round at Flushing Meadows for the accidental incident that resulted in a line judge being struck in the throat with a ball.
The maximum fine for that infraction is listed as $20,000 ($A27,500) in the grand slam rule book - the most a player can be fined for unsportsmanlike conduct - although Djokovic was slugged $10,000 ($A13,750) for that violation.
Those two fines are in addition to losing his $250,000 ($A345,000) in prize money for making it to the fourth round at the US Open.
To put the money in context, Djokovic has earned more than $140 million ($A192m) in prize money over his career, aside from millions more in endorsement deals.
However, the financial hit pales in comparison to the public fallout for the world No.1.
McEnroe, himself no stranger to grand slam defaults, accused Djokovic of making a "rookie mistake" after the incident, which saw the Serb tossed out of the tournament towards the end of his first set against Pablo Carreno Busta.
Djokovic tweeted an apology hours after the incident.
However, having already courted controversy this year by staging an ill-fated tournament amid the coronavirus pandemic and being instrumental in the creation of a controversial new players association to, McEnroe believes Djokovic will struggle to live the latest incident down.
"The pressure just got to him, I think," McEnroe told ESPN.
"A lot's been going on off the court, it's obviously affected him and now whether he likes it or not he's going to be the bad guy for the rest of his career.
"It was a rookie mistake made by him to hit a ball back where he wasn't even looking where he was hitting it.
"He's been there and done that, and certainly I know from some experience that you've got to be careful out there."
McEnroe was the first player to be defaulted from a grand slam tournament at the 1990 Australian Open, after a series of code violations during his match against Mikael Pernfors.