Kostas Manolas feels Radja Nainggolan should leave Roma.

The midfielder has been linked with Chelsea.

He said: “Nainggolan doesn't like the rain, but he is among the best midfielders in the world and has to get accustomed to that too if he wants to play in the best teams. He can do it, because he's a phenomenon.

“Let's be honest, we're not up to the standard of Barcelona, Bayern Munich and Real Madrid."