"I don't think he's the guy," Rio Ferdinand says of Viktor Gyokeres.
"I've watched him probably three times really, really closely. And three times I've gone: 'He ain't getting that opportunity in the Prem.'"
Gyokeres has scored a phenomenal 97 goals in 102 appearances for Sporting, also contributing 26 assists.
The Sweden forward averaged more than a goal per game last season, with 54 in 52 appearances.
But when he was being linked with Manchester United, Ferdinand said he was not convinced Gyokeres was a good fit for a team in England's top flight.