Willian accepts he must be at his best every day to make it with Chelsea.
The Brazilian produced arguably his best performance of the season to date during Saturday's 3-0 win against Aston Villa.
"I think I have to prove myself on a daily basis while I'm at Chelsea, kill a lion each time, and I'm dedicated to that mission, to give my best," he told chelseafc.com.
"The expression (kill a lion) comes from Brazil; when I started playing my dad would use it all the time as a way of instilling confidence in me and showing that if you work hard every day results will occur."
