The top clubs saw their average value decline to $632 million for the 2008/09 season from $691 million, said Forbes magazine. Team values are based on past team sale prices and current stadium revenue.
Fifteen teams on the list saw their values decline, with one other remaining unchanged.
However, the strengthening U.S. dollar over the past year skewed the numbers as the average value in euros rose 2.7 percent to 451 million from 439 million, Forbes said.
Leading the way again for the sixth consecutive year was Britain's Manchester United, owned by the Glazer family which also owns the National Football League's Tampa Bay Buccaneers, Forbes said. United is worth $1.8 billion, down 2 percent from the previous year.
The magazine also estimated that Manchester United, whose fans want the Glazers to sell after loading the team with debt, was the most profitable football team last year with $150 million in operating income.
In comparison, the most valuable Major League Baseball team is the New York Yankees, worth an estimated $1.6 billion, while the most valuable NFL team is the Dallas Cowboys, valued at $1.65 billion last September, according to Forbes.
Rounding out football's top five are Real Madrid (worth $1.32 billion, down 2 percent), Arsenal ($1.18 billion, down 2 percent), Barcelona ($1 billion, up 4 percent) and Bayern Munich ($990 million, down 11 percent), according to Forbes.
Arsenal has been the subject of speculation as large shareholders Stan Kroenke and Alisher Usmanov have each raised their stakes to just below the 30 percent threshold that would require a mandatory takeover offer.
The ranks of teams worth $1 billion or more shrank by one as Bayern Munich and Liverpool both dropped off the list, while Barcelona joined it, according to the magazine.
Teams rated No. 6, 7 and 9 (Liverpool, AC Milan and Chelsea) each saw their values fall 19 percent, Forbes said. Liverpool is being sold by American businessmen Thomas Hicks and George Gillett.
The biggest loser on the list was Newcastle United at No. 20, which saw its value fall 30 percent to $198 million, Forbes said. The biggest winner was Inter Milan at No. 10, with its value up 12 percent to $413 million.
The complete rankings can be found on the magazine's website at www.forbes.com/soccer.
