Manchester United have signed the UK's biggest shirt sponsorship deal.
The club is currently sponsored by Vodafone
The agreement with insurer American International Group (AIG) is worth £56.5m over four years, the club said.
United have had to find a new backer after current sponsor Vodafone decided to end its £9m-a-year agreement from the end of this season.
The deal is seen as key to United as they look to bolster their squad to help them challenge for domestic and European honours.
Off and on the pitch, United have undergone a slight wobble during the past couple of years.
Earlier this year, a survey said that Real Madrid had leapfrogged Manchester United to become the world's richest football club in terms of income.
Tamoil - Juventus, £15m a year
BenQ - Real Madrid, £14m a year (from 2006)
T-Mobile - Bayern Munich, £11.4m a year
Samsung - Chelsea, £10m a year
On the pitch, Chelsea have dominated the domestic league and United have failed to make an impression in European competitions.
The club hopes that the shirt deal will go a long way towards helping to finance a recovery.
However, United manager Sir Alex Ferguson said the club's spending policy would remain the same.
"The financial foundation will benefit the club as a whole and we can look forward to years of progress through that," he said.
"But for me it's always going to be about how we can improve the team and nothing changes in that respect.
"I go to (chief executive) David Gill and say 'this is a player I'd like', then we assess how much it's going to cost and take it from there."
The new shirt deal has not been without controversy. Earlier this week United were accused of "double dealing" by online casino firm Mansion.
The company's chief negotiator claimed that Mansion and United had verbally agreed to a £70m shirt sponsorship deal before the football club pulled out.
The club countered that it never holds exclusive talks and it was perfectly entitled to hold discussions with other firms.
Previously, the UK's biggest shirt deal was Chelsea's current £50m five-year agreement with Samsung.
United's search for a new backer was sparked after Vodafone said in November that it would start sponsoring the Uefa Champions League, both as an official partner and the official mobile network of the competition.
The world's largest mobile phone company by revenue said it would continue to work with United, but that when the Champions League opportunity arose it was "too good to let go".
The telecoms giant first started sponsoring United in 2000 but decided to take advantage of a get-out clause after the club was taken over by US sports magnate Malcolm Glazer.