Real Madrid headed a trio of European soccer clubs at the top of a list of the world's 50 most valuable sports teams released by Forbes on Monday which was dominated by National Football League (NFL) franchises.

The nine-times European champions were worth $3.3 billion (2.1 billion pounds), up from $1.88 billion last year, due in large part to increased revenue from deals with Adidas and Emirates Airlines, Forbes said in a statement.

Manchester United (3.17 billion) swapped places with Real and sit in second spot while Spanish soccer champions Barcelona (2.6 billion) moved up five places to third.

Major League Baseball's (MLB) New York Yankees ($2.3 billion) fell one spot to fourth, followed by the NFL's Dallas Cowboys ($2.1 billion) and New England Patriots ($1.6 billion).

Rounding out the top 10 were MLB's Los Angeles Dodgers ($1.6 billion), the NFL's Washington Redskins and New York Giants, and London-based soccer club Arsenal ($1.3 billion).

With 30 teams in the top 50, the NFL occupies 60 percent of this year's list. The average value of the top 50 teams is $1.24 billion, which is a 16 percent increase from last year.

The 20 non-NFL teams in the top 50 are comprised of seven each from MLB and soccer, three from the National Basketball Association (NBA), two from motor racing and one from the National Hockey League (NHL).