Chelsea hero Michael Ballack says Maurizio Sarri's players need to toughen up to take the team to a new level.

Ballack was a key part of the side under Jose Mourinho and Carlo Ancelotti that turned Chelsea into part of the European elite.

He told The Sun: “It's difficult to compare teams across the generations. The philosophy of this team is different.

“When I joined Chelsea in 2006 I came to a really strong team that stayed together for a number of years.

“We had a lot of leaders in the squad, national team captains, big players, as well as coaches with big characters.

“I see a more technical Chelsea side now.

"If they want to be top again, there are a few little things I can think of.

“The key one is the team's mentality. That is so important.

“But also the ability of the coach to give the right spirit to the team."

Ballack added: “They have a few players who have been there for a while, the likes of David Luiz, and others, and they need to lead the team to win trophies.

"That's really important.

“You cannot win without that type of player, someone who lives that feeling, who lives it totally to deliver that mentality, to the whole group.

“That winning mentality is vital to success and lifting trophies. It is not easy to have."