The BBC's David Ornstein revealed the news on Twitter:
Carrick went over on ankle during training in the last 2 days. Worse than a sprain but full extent unclear. Looking at around 10 weeks #mufc— David Ornstein (@bbcsport_david) July 17, 2014
United's official Twitter account confirmed Carrick's surgery and recovery timetable:
BREAKING: Michael Carrick has had surgery this morning on his left ankle ligaments and will be out for 10-12 weeks. #mufc— Manchester United (@ManUtd) July 17, 2014
The injury is a huge blow for the 32-year-old Carrick, who would have been hoping to impress new manager Louis van Gaal during the Dutchman's first week in charge at Old Trafford.
Ben Jefferson of the Daily Express had more on the breaking news: "Carrick is set to be out until October after undergoing surgery this morning on a chipped bone in his ankle. Carrick went over on his ankle shortly after returning to pre-season training and is now set to miss the next 10 weeks of action."
The England international played 29 Premier League games for the Red Devils last season, as per Whoscored.com, and has been a key player in the team since joining United from Tottenham Hotspur in June 2006.
Michael Carrick has completed 539 long passes in the Premier League over the past 3 seasons, more than any Man Utd player.— Squawka Football (@Squawka) July 17, 2014
Carrick's absence will give new signing Ander Herrera a great opportunity to impress during United's pre-season schedule. The 24-year-old joined United in a £28 million move from Athletic Bilbao this summer.
If the early prognosis is correct, Carrick will miss seven league games.
United kick off their tour of the USA against the LA Galaxy on July 24, and they begin their Premier League campaign against Swansea City on August 16.