Conor McGregor accused Floyd Mayweather of ducking a face-off four days before they collide in the biggest fight of all time.A mix-up over the timing for their stage arrivals outside the T-Mobile Arena made for an unscheduled crossing of their paths.The Irishman, who also had a confrontation with former sparring partner Paulie Malignaggi during the grand arrival, was supposed to step out and appear for the fans first.McGregor was originally scheduled to arrive at 1.30pm, but kept his loyal fans waiting for well over an hour and a half in 37-degree heat before Mayweather decided to jump the gun and step onto the stage ahead of his opponent.The 40-year-old wore a casual shirt and glasses as he made his way through the hoards of photographers and greeted fans, many of whom appeared to make their allegiance towards McGregor clear with jeers and boos.The UFC man said later: "We we’re supposed to have a face-off and then there was no face-off."I seen him and said ‘What, you afraid of a face-off?’ and he came forward."Little bit of pushing and shoving and that was it. The usual handbags."You can watch Mayweather and McGregor's team get into the altercation in the footage below.And, it was not the only confrontation McGregor would have during the day, as he also clashed with Paulie Malignaggi. Mayweather and McGregor have both predicted they will knock the other out on Saturday night in what is likely to become the first billion-dollar boxing match.Mayweather said: "The fight is not going the distance, no matter what he says. He's getting knocked out."More footage of McGregor and Mayweather's team can be watched in the below video.

When advised of that prediction, McGregor responded by saying: "I believe I am going to knock him down in the first round because be sure I am going to start fast."

The final press conference before the fight will be the last opportunity for the famously talkative opponents to trade insults and perhaps steal a mental advantage ahead of their bout.