Four become five: Conor McGregor and fiancee Dee Devlin welcome Rian into the world

"Healthy baby boy delivered! Baby and Mammy Wonder Woman are doing great! God I thank you for everything you give to me and my family in this world."

Conor McGregor's fiancee has given birth to their third child and the UFC star shared the exciting news of it being 'a healthy baby boy'.

The former two-division world champion shared a post of him holding his newborn on Instagram.

He wrote: "The McGregor Clan is now a family of 5.

"Healthy baby boy delivered! Baby and Mammy Wonder Woman are doing great! God I thank you for everything you give to me and my family in this world.

"My newborn son, Rían McGregor."

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A post shared by Conor McGregor Official (@thenotoriousmma)

The child is their third child together with Dee Devlin, McGregor's partner, also conceiving Conor Jack, 4, and Croia, 2.

The Irishman is preparing to avenge his devastating second-round defeat to Dustin Poirier this summer.

The pair will engage in a trilogy fight and McGregor is looking to get back to winning ways having won just once in his last three fights.

His other two defeats have come against Khabib Nurmagomedov in 2018 and Floyd Mayweather in 2017.

McGregor has predicted his eldest son to follow in his footsteps as a Mixed Martial Artist.

Conor McGregor believes Conor Jack will become a second-generation McGregor in MMA[photo: Conor McGregor/Instagram]

McGregor said in January: "He will certainly be skilled as a fighter. He's already skilled as a fighter.

"He's got phenomenal power and kicks and dexterity in his legs.

"He's going through all the disciplines and he's loving them - it's not like I'm trying to put them on to him.

"As time goes on will he want to compete? I'm not sure but he certainly will be skilled to do so."