Psychologists have long held the theory that a bad dress rehearsal portends to a great opening night, and Tyson Fury's less-than-convincing performance on stage in Sin City will have alarm bells ringing in the knowledgeable circles around the 'Gypsy King'.
For this was a de facto dress rehearsal fight for the mega-millions rematch with Deontay Wilder for the World Boxing Council heavyweight title next year.
Fury prides himself on honesty, and he will know he "won ugly" - as they say - in Las Vegas. It was of no surprise, either, that Fury's father, John - a former professional heavyweight boxer and bareknuckle fighter - weighed in powerfully and with alacrity that his son "looked as weak as a kitten" against Otto Wallin.
Wallin took - or rather managed to soak up - five rounds of heavy punishment from Fury from rounds six to 11, before battling back in the 12th to trouble the still undefeated and unofficial No 1 in the heavyweight division.
The fights storylines will centre around how the 6ft 9ins tall, 18-and-a half stone Traveller from Lancashire contended after being cut badly above the right eye from a left hook in the third round. Yet Fury's father voiced what many of us witnessed: a lack of snap and power in Fury's attacks, his timing off, and even his defence unusually leaky.
Apart from the horrific gash which did undoubtedly present issues for Fury and, which on another night with another referee and ringside physician, might have meant the fight stopped which would have given Wallin the decision by technical stoppage, there were still major problems for the favourite.
Going into the last round and way ahead on the cards, the boxer being touted as the 'lineal champion' was even forced to hang on to avoid a turnaround as Wallin caught Fury heavily and rallied.
Honesty is required, here. Wallin, ranked highly by two of the world sanctioning bodies, but in reality a rank outsider on the greatest stage of his life, comfortably lasted 12 rounds with Fury, at his lightest for this fight since he fought Wladimir Klitschko just under four years ago in claiming the world No 1 position in boxing's blue riband division.
There is concern that Fury, having ballooned to 28 stone, before losing the weight and overcoming mental illness and thoughts of suicide with two-and-a-half years spent in the wilderness, is now zealously over-training. This will need to be looked at.
But there are two sides to Fury having been forced the distance by Wallin, though, and indeed from the critique meted out by his father moreover, there are pluses.
The 36 minutes of live action - plus the two rounds against Tom Schwarz three months ago - have given him enough ring time since his monumental battle of Los Angeles with Wilder last December; and the wake-up call from his old man will sound long and loud in his head.
Fury is from pure fighting stock and the 31-year-old has people around him who know and understand the sport. Forget the promotional stuff for a moment, the theatrics and the selling of the 'Gypsy King' character and brand in the United States under the enormous broadcast banner of ESPN. The cut will need to heal, but it was a lethargic performance from Fury. The excuse will be made about the lack of vision in his right eye for three quarters of the fight, but the ever-alert and calm-under-pressure trainer Ben Davison will know that this version of Fury will need to be back to his most nimble, dexterous and effective in order to claim victory over the 'Bronze Bomber' from Alabama at the second time of asking.
This 'bad dress rehearsal' is perhaps good for the real thing. Don't be fooled; Fury was way off his own standards in this fight. The man himself will know that, believe me. But he simply has to be back to his elusive best when the call of the Wilder comes.