Felix has been heavily linked with a move to the English top-flight with Chelsea, Arsenal and Man United all interested.
The Portugal international is viewed as one of the most highly-rated players in Europe but has endured a turbulent spell under Atletico Madrid boss Diego Simeone and is reportedly open to leaving.
Chelsea want to bolster Graham Potter’s attacking options, having scored just 19 goals in 15 Premier League games this season.
Arsenal are also keen to sign a new forward following the injury star striker Gabriel Jesus suffered during the Qatar World Cup.
Manchester United will be in the market for a new striker in January having released Cristiano Ronaldo during the World Cup.
But the Premier League giants have been warned against signing Felix, with Merson claiming he is too ‘lightweight’ for the Premier League and incapable of ‘bullying’ defenders.
‘Chelsea need to build a team that can challenge for the title on a consistent basis. But for me they’ve got to be patient.
‘They chased Graham Potter down because they saw how he got Brighton playing over time, and I think they need to give him time too.
‘Just be patient. He’s buying younger players so he’s looking at this as a four or five-year plan, I would have thought. It’s no good chopping and changing the manager if you’re doing that.’