Midfielder Fernandes has won two full caps for Portugal

The 20-year-old is on a season-long loan deal at Fratton Park, with a view to a �7m move from Benfica, but reports claim Manchester United may swoop.

"I think the permanent deal clicks in for us when Fernandes plays a few more games," said Redknapp.

"I think he plays X amount of games and then we take up the option to buy him. As far as I know it is a tied-up deal."

Fernandes twice failed a medical at Fratton Park in the summer because of a groin problem, so Benfica allowed the Portugal international to move on loan.

We are hoping he will become a top, top player for us and I'm convinced that will happen Harry Redknapp on Manuel Fernandes

He has since recovered from injury and has started one game, scoring a spectacular goal against Mansfield in the Carling Cup.

He came on as a substitute against Bolton for his Premiership debut but missed out on the squad for the game against Tottenham on Sunday.

"Fernandes is a fantastic player and sooner or later he is going to have to play for us," added Redknapp.

"Although he has been out a long time with his injury, people know him here in this country.

"He played in the Champions League for Benfica last season at Old Trafford and people from there certainly know about him.

"But we are hoping he will become a top, top player for us and I'm convinced that will happen."