This is the opinion of Sky Sports, the Chelsea fan and former Arsenal striker Paul Merson.Kepa joined the Blues from Athletic Bilbao on Wednesday to become the most expensive goalkeeper in the world at £ 71.6 million. The Spaniard has the unenviable task of replacing Thibaut Courtois in Chelsea's goal after the Belgian arrived at Real Madrid for around £ 35m. He was immediately launched into action in the first Premier League game in Chelsea at Huddersfield. The 23-year-old has signed a seven-year contract at Stamford Bridge and Merson thinks it will end up being the real deal. But he says he has never seen a Kepa goalkeeper be what he would call "world class". "They sold him for £ 35 million in Courtois, so he has about £ 35 million for this goalkeeper," If this goalkeeper will be there for seven years, it will be perfect. "If they buy one of the other goalkeepers (they were connected) and make mistakes like do and can do, you're watching Christ Mas has spent another 30 million pounds for another goalkeeper. "They just went" well, this is our goalkeeper for at least the next five years. " The only problem I have is that I have never seen a world-class goalkeeper at 23, ever. "Kepa has only one cap for Spain, coming with a 5-0 win over Costa Rica last November.