The owners of Manchester United said Tuesday they were open to selling the English football giants, in the same day as Cristiano Ronaldo's controversial second spell at the club came to an end with "immediate effect" as the club announced.

Weeks of turbulence at Old Trafford appeared to have come to an end when the club announced Ronaldo was leaving with "immediate effect."

That dramatic announcement was eclipsed just hours later by the news that the United States-based Glazer family, who have owned United for 17 years, could be on their way out as well.

An earlier report had speculated that the United States-based owners of Manchester United, the Glazer family, could sell the Premier League giants. Later, a statement issued by the club said: "The board will consider all strategic alternatives, including new investment into the club, a sale, or other transactions involving the company."

The Glazer family have owned United for 17 years but their reign has been marked by declining on-field performance and repeated fan protests.

The news came just hours after the mutual termination of Ronaldo's contract. The Portugal forward set the stage for his Old Trafford exit last week with his outspoken television interview on TalkTV in which he said he felt "betrayed" by the club and had no respect for new manager Erik ten Hag.

"Cristiano Ronaldo is to leave Manchester United by mutual agreement, with immediate effect," said a United statement. "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."

'Love United, love the fans'

Ronaldo issued a statement of his own, saying: "Following conversations with Manchester United we have mutually agreed to end our contract early. I love Manchester United and I love the fans, that will never ever change. However, it feels like the right time for me to seek a new challenge.

"I wish the team every success for the remainder of the season and for the future."

As well as criticizing the Old Trafford hierarchy and Ten Hag during his interview, the 37-year-old Ronaldo, currently with the Portugal squad at the World Cup in Qatar, was scathing about the club's U.S. owners.

Ronaldo said the Glazer family cared far more about the money-making potential of United than results on the pitch. The Glazers have long been unpopular with the United faithful.

Sky News reported Tuesday the Glazers were preparing to formally announce their intention to examine potential sources of outside investment that could include either an auction of United, with a full or partial sale, or strategic partnership with third parties other possible options. The statement issued later by the club confirmed those reports.

United have not won the Premier League title since 2013 and have sacked several managers following the retirement of Sir Alex Ferguson.

They have also failed to qualify for this season's Champions League, a setback which may have encouraged Ronaldo in appearing to push for a move in the pre-season transfer window.

However, leading English and European clubs opted against moving for a player who, for all he recently scored the 700th goal of his club career, is not the force he once was yet still commands a reported weekly pay packet at United of around £500,000 ($593,000).

The five-time Ballon d'Or winner has, however, reportedly held talks with Bayern Munich and been linked with an emotional return to Sporting Lisbon, where he came through the youth ranks.

'Both parties happy'

Former Manchester United defender Rio Ferdinand said both Ronaldo and the club had got what they wanted.

"Cristiano obviously did that interview with the mindset that he wasn't happy and wanted to get out of the club," Ferdinand, who played alongside Ronaldo at Old Trafford, told the BBC. "He made that very clear.

"I think Erik ten Hag got what he wanted in this situation as well. Both parties are happy and we can move on."

Ronaldo has undoubtedly been angered by his reduced status at United, with the club no longer at the summit of English football.

In 2009 he left a United who were one of the top teams in Europe but the side he rejoined limped to a sixth-place finish in the Premier League despite his 24 goals in all competitions.

Ronaldo made his name in his first spell at Old Trafford, developing from a prodigiously gifted teenager when he arrived in 2003 into one of the best forwards in world football.

He won his first Champions League trophy and first Ballon d'Or during a trophy-laden spell under Ferguson.

He left United after six years for Real Madrid, where he became the club's greatest goalscorer, winning the Champions League four more times.

Ronaldo spent three years at Juventus from 2018 before a return to Manchester.

But he has been a peripheral figure this season in an improving side under Ten Hag and was recently disciplined for refusing to come on as a substitute.

Ronaldo, who has scored just three goals this season, had returned to the team in recent weeks and even captained the Red Devils in a 3-1 loss at Aston Villa, though he was not in the squad for United's final match before the World Cup break.

With a world-record 117 international goals, he is captaining Portugal at his fifth World Cup.

The Euro 2016 winners open their campaign in Qatar against Ghana on Thursday.