Description:Thibaut Courtois' rapid development into one of the best young goalkeepers in the world at Atletico Madrid has given Chelsea an unexpected problem which many other clubs can only wish they had to deal with. The 20-year-old Belgium international was bought by Chelsea as a long-term replacement for Peter Cech on a five-year contract from Racing Genk in 2011, and was immediately loaned out to Spain.(1:22)