Tyson Fury's promoter Frank Warren has warned the British fighter to learn from Anthony Joshua's shock defeat to Andy Ruiz Jr. as he prepares for his next opponent.
Fury (27-0-1, 19 KO's) fights undefeated German Tom Schwarz at the MGM Grand Garden Arena in Las Vegas on June 15 and is the heavy favourite going into the contest.
But Warren believes Joshua's unexpected setback at Madison Square Garden must act as a reminder to his fighter to avoid any complacency.
"Tyson Fury will have to be very much on his guard. People keep talking about easy or knockover opponents, but Tyson has got a job to do on June 15," Warren wrote in a column for frankwarren.com.
"Tom Schwarz has got the chance to change his life in Las Vegas. He is a big guy who can punch and is also young and unbeaten. He will take inspiration from Ruiz.
"Tyson though is not complacent and has been training hard since his fight with Deontay Wilder [in December 2018]. If he did think he was in for an easy night's work, he might just think again after watching a big favourite tumble in New York."
Joshua suffered a stunning knockout at the hands of Ruiz in the seventh round of his inaugural U.S. fight and saw his three heavyweight world title belts change hands to the joyous Mexican in one of the most surprising outcomes of modern boxing history.
Ruiz survived a knockdown in the third round and rallied to drop Joshua twice later in the round and then twice more before stopping his opponent in a totally unexpected finale.
But Warren said he was not surprised to see Joshua's defences penetrated by Ruiz.
"The warning signs of what transpired at Madison Square Garden have been evident for some time now," he said. "I've felt, probably since the Dillian Whyte fight [in December 2015], that he hasn't improved his defences as a professional.
"Suffering defeat in such a manner to Ruiz did come as a surprise, but the vulnerability of Joshua has been there for all to see over a number of fights now. He has been clipped by a few good opponents and nothing seems to have been done to minimise the risk.
"I'm sure there will be an inquest by Joshua and he will have some big questions to answer."
Fury, 30, is looking to secure a title rematch with WBC champion Wilder but could risk losing that opportunity if he fails to overcome Schwarz.
The pair battled to a pulsating draw in their first bout in December 2018, with Fury climbing off the canvas after he was knocked down in the 12th round despite controlling the fight for long periods.
Wilder will fight Luis Ortiz Jr. next and has said he will take on a rematch with Fury if he wins.
Meanwhile for Joshua a rematch with Ruiz remains likely, but the defeat has moved him even further away from the super-fight with Wilder he craves.
Warren said he believes most heavyweights will now be thinking the former champion is vulnerable.
"After the fight he really didn't seem too distressed over being stopped and, while you might say he was being a good loser, there was something about it all that didn't sit right with me -- it just seemed to be quite a strange situation all around," Warren said of Joshua's defeat.
"Looking at the bigger picture, talk has now turned towards a rematch later this year that will be anything but a foregone conclusion as far as Joshua is concerned. Ruiz will have a full camp to prepare knowing that he has got the beating of him.
"You only have to look at the difference between Tyson Fury getting knocked down by the biggest puncher in boxing and then getting up and winning the round, as opposed to Joshua who went into his shell. He just couldn't get himself right and it might just be that Ruiz has got his number.
"In fact, from watching it all unfold, most heavyweights might think they have got his number now."