McGregor is stepping outside his comfort zone of the UFC octagon to fight the greatest boxer of the past generation. The Times consulted those who know McGregor and boxing best to assess if the underdog from Ireland can shock Mayweather.

Michael Conlan 2016 Olympian (Ireland) "The only way I can give him a chance is through self-belief. He's got self-belief like I've never seen in anyone before." Jessie Magdaleno WBO junior featherweight world champion "It's very hard to believe [McGregor will win]...I do give him his props on being very respectful to the sport, and how courageous he is getting in there and taking a tough task like Mayweather." Manny Robles Southland boxing trainer of two reigning world champions "I respect his sport... I don't follow UFC, but I hear a lot about this guy, and he's supposed to be at the top of his game...but this isn't the UFC, this is boxing."

Inside the ring This will be McGregor’s first professional bout in a boxing ring. Professional boxing rings can vary in size depending on the competition, but most major bouts use a 20-by-20-foot ring. A UFC octagon is larger and lacks the sharp corners of a boxing ring. The UFC’s octagon melds boxing’s square ring with wrestling’s circular ring. Boxing ring (WBO specifications) UFC Octagon What McGregor won't (or shouldn't) do Several moves that rules allow McGregor to use in UFC are illegal in boxing. McGregor and Mayweather say their contract states they must fight using boxing’s classic Queensberry rules. If McGregor violates those rules, Mayweather has said McGregor will forfeit a significant amount of his purse, and can be sued if the violation injures Mayweather. According to Conlan, the threat of losing a significant amount of money is enough for McGregor to resist the temptation of using the kicks, knees and elbows permissible in MMA action. Michael Conlan "When that type of money is on the line, you're not going to forget that stuff. It doesn't matter if you're frustrated or angry...you're not going to lose $50 million or whatever he's trying to defend." Moves allowed in UFC that are not allowed in boxing Hitting opponents when they're down McGregor did this to finish off former featherweight champion Jose Aldo, but in boxing, a knocked down opponent is allowed time to recover in a standing eight-count. Kicking McGregor relied on kicks routinely in defeating Chad Mendes and Nate Diaz to set up his powerful left-handed punch. Elbowing While Mayweather has a storied history of coyly delivering elbows away from the referee's view, McGregor is not allowed to throw the Muay Thai blows permitted in the UFC.

Experience McGregor is a striking specialist who’s 21-3 with 18 knockouts and has never been knocked out. The Irishman’s endurance will be tested by Mayweather, who has dominated 12-round fights against the likes of Manny Pacquiao and Canelo Alvarez. That’s 36 minutes of work. McGregor's longest fight totaled 25 minutes. How their records compare Mayweather: More likely to go the distance As Mayweather has aged and moved up in weight during his extended career, the more likely he's been to go 12 rounds and let the judges decide the winner. McGregor: Quicker, decisive finishes McGregor, whose professional career is nearly 15 years shorter than Mayweather's, has shown he prefers to pursue a rapid finish. Note: Exact times for McGregor's first two professional fights not available. Because of Mayweather's tendency to fight through the final round, Robles says McGregor must be prepared to go the distance. Manuel Robles "Mayweather's going to come in and fight his fight...gonna box the lights out of [McGregor] and counterpunch him for 12 rounds if he has to."

How they're training While creature-of-habit Mayweather has returned to his home gym in Las Vegas to prepare under his father/trainer, Floyd Mayweather Sr., he said age has led him to curtail working out on consecutive days. McGregor has been in Las Vegas for the last few months but has declined to align with a world-class boxing trainer, instead maintaining his relationship with head MMA coach John Kavanagh. We asked Conlan, Magdaleno and Robles to inspect videos of McGregor and Mayweather boxing. Here's what they had to say: Conor McGregor's training video McGregor worked out on bags during his recent media-day session at UFC headquarters in Las Vegas. Boxing experts have scoffed at his punching style and even a warm-up routine he displayed that day. Manuel Robles "He looks very green...how much can you really learn in a couple of months?" Floyd Mayweather's training video Showing the sophisticated punching style he’s studiously developed since his days boxing as a child, Mayweather stands as the most disciplined, committed fighter of the past 25 years, and his recent workout on his media day revealed no noticeable slippage. Jessie Magdaleno "You can just see the difference between the way Mayweather hits the bag and [McGregor]...he's 40 but he trains like a 21-year-old."

How McGregor could win The extremely confident Irishman has risen from non-televised UFC undercard action to a string of impressive triumphs that included dethroning longtime featherweight champion Jose Aldo, moving up 25 pounds above that weight class to avenge a loss to strong-boxing UFC foe Nate Diaz, then dominating gritty lightweight champion Eddie Alvarez. He says he believes he can topple Mayweather by relying not so much on pure boxing skill but on his ability to pounce on the openings he’s become used to spotting in the UFC cage. Michael Conlan "His best tactic is to go in and give it his all as early as possible – put it all on the line – and if it doesn't work he'll go out on a sheet." Jessie Magdaleno "Give [Mayweather] a surprise and go hard, and see how Floyd reacts to it - and try to do it as soon as possible because 36 minutes is a long time." Manny Robles "The problem is, it's not gonna be a surprise anymore. I can't imagine McGregor taking his time and trying to box the guy and measure him up...you can't beat Mayweather at his game."