Agent Mel Stein believes Manchester United are under-paying Wayne Rooney.

Stein was giving expert witness evidence at a hearing in which Wayne and Coleen Rooney are being sued by Proactive, the sports agency Rooney signed with in 2003 aged just 17 after signing his first professional football contract with his home town club Everton.

Stein said firms who agree sponsorships with top players, "want to keep their clients happy".

He added: "I'm simply saying, in the real world, people do in the world of sport, renegotiate contracts, however long they are, at early stages and companies and clubs sit down and renegotiate because they want to have a happy client.

"Mr Rooney, from my understanding, I don't know precisely what he's on, you see reports in newspapers and get some idea, is underpaid.

"When he renegotiates his contract he will get a lot more money.

"It is likely to improve after the World Cup."