Chris Smalling can still be a key defender for Manchester United, according to former centre-half Nemanja Vidic.

Smalling made his first league start on Sunday in the defeat by Watford, having fallen behind Eric Bailly and Daley Blind in the United pecking order, and struggled in the 3-1 reverse, almost giving away a goal in a collision with goalkeeper David de Gea.

But Vidic insists he can return to the form that saw him become a key player under Louis van Gaal.

Chris Smalling started his first Premier League game of the season against Watford

The Manchester United defender struggled during the 3-1 defeat, but will improve says Vidic

Smalling and David de Gea collided early on and nearly cost the visitors a goal

'I still believe in Chris Smalling,' Vidic told Four Four Two. 'He did well last season and he can improve and do better. He has the mentality to defend, and the physical size to do it. He likes to defend. With a good partner he can be even better.'

The Serbian, who retired this year after finishing his career at Inter Milan, admitted that defending has changed since he became a dominant force at the back for United.

But the five-time Premier League champion insisted that he likes 'defenders to defend' rather than seeing midfielders drafted in at the back.

Nemanja Vidic, who won five Premier League titles, insists the Englishman can still get better

Vidic says he likes defenders who defend, and would like to see Smalling start for United

'Football is changing, with Barcelona being the best example of that. Midfielders play as centre-backs. But if you face Barcelona then you are playing against a team who will always attack,'

'Even at United, though, Daley Blind and Michael Carrick play as defenders. Left-backs can play as central defenders. That wouldn't happen before.

'Is the game changing or are there not enough defenders? I'm not sure. Do we want defenders any more? Some managers don't know what they want.

'I know what I like: defenders to defend. Defenders bring balance to a team and having too many non-defenders can lose that.