Drogba, 34, scored 157 goals in 341 appearances for Chelsea over eight years, including the winner against Ferguson's United in the 2007 FA Cup final.

The Ivory Coast international also headed the late equaliser in last season's Champions League final against Bayern Munich and then netted the winning penalty in the shootout which followed.

Drogba signed a two-year-and-half-year contract with Shanghai last month, joining former Chelsea team-mate Nicolas Anelka at the Chinese outfit.

"When you think of the season he's just had, I must say it is a big boost for us that Drogba is leaving Chelsea," Ferguson told The People.

"He scored that fantastic goal in the final with two minutes to go and his goal scoring record in the big games, in big finals, is incredible.

"As far as I was concerned, he won the Champions League for Chelsea."