Miami had denied they were taking part in the tournament when plans were initially announced in November.

"These matches will offer important tests for our team," Inter Miami sporting director Chris Henderson said.

"We're excited for our group to get the chance to go up against teams with as much quality as Al-Hilal and Al-Nassr."

Widely regarded as all-time greats, forwards Messi, 36, and Ronaldo first met in 2008 when Barcelona beat Manchester United 2-0 in the Champions League final and have faced each other on a further 34 occasions, with the Argentine winning 16 times and the Portuguese coming out on top in 10 fixtures, while nine have ended in a draw.

Across those 35 encounters, Messi has scored 21 goals and laid on 12 assists, while Ronaldo, 38, has 20 goals and one assist to his name.

Inter Miami finished 14th in the Eastern Conference last season and they won the Leagues Cup, with Messi, who joined the club in July, scoring 10 goals across seven games to help the club lift their first trophy.

Saudi Arabia has invested vast sums into sports, football in particular, with Ronaldo, Karim Benzema, Sadio Mane, N'Golo Kante and Jordan Henderson all signing for Saudi Pro League clubs over recent years.

Campaigners say investment into sport is being used to distract from long-standing reputation issues such as Saudi Arabia's human rights record, the 2018 murder of journalist Jamal Khashoggi, and the war in Yemen - a process known as 'sportswashing', although the Kingdom's sports minister, Prince Abdulaziz bin Turki Al Faisal, says those claims are "very shallow."