Diogo Dalot could be a mainstay at Manchester United for the next 10 years after impressing on debut in the Red Devils' Champions League victory over Young Boys, says boss Jose Mourinho.
The Portuguese said the 19-year-old was the "best young full-back in Europe" after signing him from Porto in June.
And Dalot, whose initial progress was hampered by a knee injury, was assured on his first start.
"Everyone could see the potential," said Mourinho.
United paid £19m to sign Dalot in the summer, despite the fact he had made just seven senior appearances.
"Everyone could see he's a 19-year-old player that has more than 10 years to play for Manchester United," Mourinho added.
"But I also want to be nice to Luke Shaw because I think Diogo and Luke played very, very well and our danger came from both of them.
"They had fantastic movement, depth, crosses, assists, were involved in the most dangerous actions and they defended well."
Paul Pogba scored twice before half-time, including a penalty, before Anthony Martial wrapped up United's comfortable victory in Switzerland.