LONDON (AFP) - New Swansea manager Carlos Carvalhal is confident his fellow Portuguese Renato Sanches can resurrect his career after failing to impress since his loan move from Bayern Munich.

The 20-year-old midfielder, who was named best young player at Euro 2016, has failed to score or provide an assist in 11 Swansea appearances.

Sanches has not started a game since Nov 29, when he was ridiculed for passing a ball into an advertising hoarding at Chelsea with no Swansea player in close attendance.

But Carvalhal believes Sanches, who cost Bayern €35 million (S$55.9 million) last May when he joined them from Benfica before Portugal won Euro 2016, will prove himself at Swansea under his management.

"I think he (Sanches) needs confidence," Carvalhal said, ahead of his Swansea bow at Watford on Saturday (Dec 30).

"It is easy to forget because he has played for Benfica and the Portuguese national team that he is still only a kid.

"He is still learning and I think he needs a role in the team.

"With time, he will understand all the different roles the players have in the team.

"But he will be involved in the dynamic and when he understands what we want, he will be a completely different player. We believe that."

Carvalhal was appointed Swansea manager on Thursday, only four days after his two-and-a-half-year spell at Championship side Sheffield Wednesday came to an end.

He has inherited a side five points from safety after only one win in 12 Premier League games, and a swift upturn in results are needed if Swansea are to be playing top-flight football for an eighth successive season next term.