The all-action affair between two top 10 ranked light-heavyweights was announced alongside four other undercard bouts.

On the same bill, one-punch knockout artist Joe Pfyer takes on dangerous Canadian middleweight Marc-Andre Barriault while featherweight stalwart Cub Swanson squares off against the always-entertaining Andre Fili.

Former Invicta champion Michelle Waterson-Gomez is also back in action against submission specialist Gillian Robertson at strawweight as is hard-hitting bantamweight Macy Chiasson, who is set to duke it out with Mayra Bueno Silva.

Garry initially reacted to Hill vs Rountree being promoted as the UFC 303 co-headliner with disbelief before adamantly insisting this would not be the case.

“I think you mean ‘Featured bout'”, Garry wrote on X yesterday.

He then took to Instagram to add: “When I read the news and see something ain’t right – I’ll be co-main mark my words #UFC303 @ufc.”

Many believed a grudge match between Colby Covington and Garry would be the co-feature attraction for UFC 303 to keep in line with the United States vs Ireland theme in the main event.

Garry has made no secret of his intention to take on Covington and claimed earlier this month that he had received a contract to face the American.

3McGregor vs Chandler is the UFC 303 main eventCredit: ESPN3Garry is targeting a fight with fierce rival CovingtonCredit: Getty

“I just wanna let everyone know I have agreed to fight with Colby Covington,” Garry wrote on Instagram on April 9.

“There is a date in place. Colby still hasn’t signed the contract.”

Covington (17-4) has been out of action since failing at his third attempt at the UFC welterweight title against Leon Edwards in December at UFC 296.

Garry (14-0) last fought in February when he defeated Geoff Neal via split decision at UFC 298.

Following his win over Neal, Garry called out ‘Chaos’ and vowed to end his career once and for all.

In response, Covington produced a crude video, claiming Garry’s wife Layla would have to fulfil degrading tasks to secure him the fight.

“Let me teach you the art of the deal, Ian, let’s come to a compromise. If you can meet these three stipulations, we got a fight,” Covington shouted.

“Stipulation number one, you and that gold-digging w**** have got to turn your Instagram comments back on, and if you turn them off before the fight, you forfeit the fight. If you turn them off during fight week or after I beat your a**, you forfeit your purse.

“Stipulation number two. Ian, we’ve heard you cry and beg on your knees, but we all know you’re not the boss and you don’t wear the pants in the relationship.

“Layla, you got 60 seconds to convince me and the people why this fight needs to happen. So put your husband in the corner, get on your hands and knees, and beg.

“Now for stipulation number three, my personal favourite. As you all might have noticed, something has been missing from my MyBookie promos lately, that’s because I’ve been saving that spot for a special someone.

“You want your 15 seconds of fame Layla? I’ll give you your 15 seconds of fame right here for America’s pick of the week.

“After I beat your husband, he’s going to sit in the corner just as he does with that cuck stuff you guys do, and he’s going to watch while you get your 15 seconds of fame.

“Ball’s in your court now cuck boy. I’ll have my lawyers raft up the papers, you got 24 hours to respond, we’ll see if you’re about that life.”