Chelsea boss Frank Lampard admits the leadership of Willian is proving crucial this season.
The Brazilian was the only player above the age of 28 in the team which defeated Crystal Palace on Saturday.
"I know Willian's qualities from playing with him, but when I looked at Willy over the last couple of years he was in and out of the team and I'm not sure; from the outside I want to see him happy, I know him and he's a happy, really easy-going lad who loves his football," said Lampard, whose final campaign at the club in 2013/14 was Willian's first.
"That was the first thing, when I looked at him at the start of the season, I saw him being huge for me and the way we want to play. Naturally, on the ball we all know his ability to go by one-v-one and shift people and then cross or get shots away is big.
"But the off-the-ball work he's done is an absolutely outstanding example for Callum Hudson-Odoi, Christian Pulisic, for other young players and wingers who think the only part of the game is going past people and crossing or shooting. He does the other side brilliantly, with absolute humility, so he's been a joy and one of the experienced players that's really helping the young boys.
"The selfless side of the game is always a starting point for me. As we work as staff here, it's how good can we be off the ball and think about on the ball afterwards. When you've got someone showing the example high up the pitch, that just reflects everywhere."
