Cristiano Ronaldo was on the verge of tears while singing the Portuguese national anthem

Cristiano Ronaldo was in tears as he sang the Portuguese national anthem ahead of their World Cup opener against Ghana.

The 37-year-old forward, who left Manchester United earlier this week by mutual agreement, became the second player to captain a country at the World Cup without being attached to a club on Thursday afternoon.

And ahead of kick-off, the five-time Ballon d'Or winner was incredibly emotional as he stood for the national anthem.

One fan commented on the moment, saying: "Ronaldo in tears during the Portugal national anthem. Realising its his last dance with Portugal. It is sad."

An emotional Cristiano Ronaldo during the Portugal national anthem, in what is likely to be his final WC.

Chills.#FIFAWorldCup pic.twitter.com/4OJBHXNLQa

— FanDuel Canada (@FanDuelCanada) November 24, 2022

It has been an eventful week for Ronaldo, who gave an extraordinary interview to Piers Morgan ahead of this winter's tournament in Qatar.

Days later and Manchester United decided to cut ties with Portugal's all-time top goalscorer after he criticised manager Erik ten Hag, the facilities at Carrington training ground and former teammates Wayne Rooney and Gary Neville.

A statement from the club read: "Cristiano Ronaldo is to leave Manchester United by mutual agreement, with immediate effect.

"The club thanks him for his immense contribution across two spells at Old Trafford, scoring 145 goals in 346 appearances, and wishes him and his family well for the future.

"Everyone at Manchester United remains focused on continuing the team’s progress under Erik ten Hag and working together to deliver success on the pitch."

All eyes were on Ronaldo as he stepped out to play his first game as a free agent.Ahead of kick-off, former teammate Roy Keane backed the forward to prove his critics wrong in the Group H clash against Ghana.

"I'm looking forward to seeing him play," Keane told ITV. "I hope he performs, I believe he will. He'll do it on the pitch and shut a few people up... all the idiots out there who have been criticising him.

"He's a great player, [I'm] lucky to have played with him and delighted to be watching him again tonight."

The former Real Madrid forward, meanwhile, released a statement on Tuesday after his Manchester United exit.

"Following talks with Manchester United, we’ve mutually agreed to end our contract," a statement read. "I love Manchester United and I love the fans, that will never ever change.

"It feels like the right time to seek a new challenge. I wish Man Utd all the best."