The Blues completed the signing of the talented teenager last summer as a deal was agreed with Brazilian side Palmeiras that could rise to £52m.
Willian will remain at the club until next summer with his excellent performances this season earning him his first four senior international caps for Brazil aged just 17 as well as praise from football icon Ronaldo.
"He's a young player and very talented,” Real Valladolid owner Ronaldo told Ben Jacobs of GiveMeSport. “He's kind of like Lamine Yamal. He will soon be a very big star in football. He's very promising and at just 17. I think he'll play for Palmeiras at the Club World Cup and then join Chelsea."
Neymar also commented on the teenager, stating he was one of the most exciting talents for the future of Brazil.
“I think Estevao is the big talent that is coming in Brazilian football,” Neymar said earlier this year. “I think he will be a genius.”
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