Conor McGregor won a thrilling decision victory in a rematch with Nate Diaz that turned into a bloody war of attrition in a fight for the ages at the T-Mobile Arena in Las Vegas on Saturday.

Both fighters landed some heavy damage but neither could find the knockout blow, and it was left to the judges to declare McGregor the winner, and set the scene for a third and final future meeting between the two.

Featherweight champ McGregor stepped up two weight classes to fight Diaz at welterweight in March, but the Californian stunned the fight world by withstanding McGregor’s opening onslaught before submitting him in the second round.

McGregor demanded a rematch which was slated for the UFC 200 event in July, but the fight was scrubbed from the card when the Irishman failed to show for a press conference to promote the event.

The bad blood between Diaz and McGregor was apparent at the pre-fight press conference on Thursday, which ended abruptly as bottles and cans were hurled between the two camps.

McGregor downed Diaz early in the first round with a stinging left hand, barely breaking sweat as he conserved energy, fighting a tactical fight featuring plenty of kicks to the front leg of his opponent.

Diaz hit the deck twice early in the second but McGregor declined to take the fight to the mat, preferring to let Diaz rise to his feet and pick his shots.

Famed for his durability, Diaz made him pay, somehow finding the energy to land two telling strikes of his own, forcing McGregor back against the cage towards the end of the second round.

Emboldened, Diaz almost finished it in the third, McGregor somehow staying on his feet despite a series of heavy blows.

With the two fighters struggling from fatigue, the final two rounds were heavy on clinches around the cage, and Diaz did not manage to take McGregor down until the final seconds of the fifth round.

McGregor is still the biggest draw in the UFC, as evidenced by his three million dollar purse for Saturday's fight, and the UFC now wants him to defend the featherweight crown he has held since defeating Jose Aldo in December last year, or to vacate it.

The Irishman spared no expense in exacting his revenge, reputedly shelling out over 300,000 dollars for an 18-week training camp.

Southpaw sparring partners with similar characteristics to the rangy Californian were flown in to a specially-built gym, where McGregor and his coaches meticulously worked out their game-plan.

Well aware that it was his lack of conditioning that caused him to founder in the March encounter, the 28-year-old featherweight champion "built up the tank," as his coach John Kavanagh put it at a book signing in Las Vegas on Thursday.

Having eaten pretty much anything that was put in front of him to get up to 170 pounds in March, this time around his nutrition was minutely planned.

Nothing was left to chance. Kavanagh also promised that the spectacular spinning kicks and strikes that McGregor has made his trademark would also be dispensed with in favour of a more energy-saving, pragmatic approach.

This fight was the first main event under the new ownership. As of Friday when the four billion dollar sale of the UFC went through, the Fertitta brothers are gone, and though Dana White has stayed on, his relationship with McGregor is undeniably strained following his decision to scrub the Irishman from the UFC 200 card.

For McGregor it was business as usual, with the Nevada State Athletic Commission revealing that he would be paid three million dollars for meeting Diaz.

His impact on Las Vegas is even greater. One store clerk confided that her Polish husband, a shuttle bus driver at the MGM Grand was hoping he would win. “The Irish fans always tip way more when McGregor wins, and nothing when he loses,” she said.

His name was also helping the bookies' tills ring all day, the odds on a McGregor win shortening as the Irish poured their money on their man, despite the pundits all going for Diaz.

When it did come, the hard-fought victory was welcomed by bus drivers and the thousands of travelling fans, but the bookies will have to wait for another opportunity to separate them from their cash.