The United States international moved to Craven Cottage from New England Revolution in January 2007 and was used sparingly last season.

However, he scored a crucial goal against Liverpool which secured the club's Premier League status and he has featured prominently this term.

He is currently the club's top scorer in the Premier League with six goals and his attacking versatility has been an asset to Roy Hodgson's side.

The deal for Dempsey will be a major boost for Fulham as the club again look to hang on to their top-flight status.

A 2-0 win at home to relegation rivals Birmingham on Saturday lifted the Cottagers out of the bottom three ahead of a last-day trip to FA Cup finalists Portsmouth.