Ralph Ellis looks at why Saturday's clash at the Manchester Arena is also a defining night for the man in George Groves' corner...
"Groves is the outsider in the Match Odds for Saturday night at [2.5] but in what is essentially a 50-50 fight I see that as a value bet."
When George Groves steps into the ring at Manchester Arena on Saturday night he won't be the only one facing a defining few rounds of his career.
It's big for Groves, no question. Having fought his way back from the devastating psychological impact of losing two mega fights with Carl Froch, and then had his next attempt to win a world title ended by Badou Jack, he's taking a huge risk putting his WBA belt on the line against Chris Eubank Junior.
But it is also a massive night for his trainer Shane McGuigan who in the space of 12 months has gone from being the undisputed king of young boxing coaches to one with huge doubts hanging over him.
McGuigan, son of boxing legend Barry, could do no wrong when he started his career at the tender age of 21 before guiding Carl Frampton to triple world titles.
He went six years without a single one of his fighters losing a contest, but then a Conrad Cummings defeat to Ronnie Mittag was followed in a few months by Frampton falling to Leo Santa Cruz and David Haye to Tony Bellew.
Frampton and Haye both left his stable, and questions were being asked all round the boxing world whether young Shane, self-styled expert in nutrition and conditioning as well as ringcraft, really knew his business.
Shane's own website hails his McGuigan gym in London as "the industry leaders in strength, fitness and weight management." It's a bold claim shattered by top fighters leaving.
That's where Groves, who began working with McGuigan when he left Paddy Fitzpatrick following his defeat to Jack, has stayed loyal and can now do so much to restore the reputation of the 29-year-old.
Groves is the outsider in the Match Odds for Saturday night at [2.5] but in what is essentially a 50-50 fight I see that as a value bet.
I remember siding with Jack when they fought in Las Vegas in 2015 because at that time it seemed to me that Groves had his confidence shot to pieces by the two Froch defeats. He'd lost that inner belief that every boxer must have.
Working with McGuigan, it seems, has restored that. Groves now trusts his own punching power again and all the more so since finally winning a world title when he beat Fedor Chudinov a year ago. He proved it by taking just four rounds to stop Jamie Cox a few months later.
You can hear it in his pre-fight interviews, he's at ease with himself again as he was leading up to the Froch fights.
Eubank, of course, is a seriously tough opponent - although there are many who doubt the quality of some of the boxers left behind in his 20 knock-out path to his IBO super middleweight title.
But when it comes to those defining nights, the trust in the guy who is in your corner, and who has taken you through all the tactics and preparation, can be a crucial factor and there's no doubt that McGuigan has relit the fire in Groves.
It promises to be an epic battle, won by fine margins, and Groves by a Decision at [5.6] in the Method of Victory market looks a good bet to me. It would also be a result to restore the good name of Shane McGuigan.