Rio Ferdinand has revealed what it would take for Sporting Lisbon star Viktor Gyokeres to reach the 'top bracket' of forwards.
The Swede, who has scored 23 goals in 18 games for Sporting this season, has become one of Europe's most sought after stars following his displays in Portugal.
Ruben Amorim spent four years at Sporting Lisbon in Portugal and helped develop Gyokeres into one of the best strikers in the world during that time before departing for United.
There have been rumours of a potential reunion between the two at Old Trafford and former Red Devils defender Ferdinand has insisted that it should happen.