Wales assistant manager Raymond Verheijen has hailed the ability of Arsenal midfielder Aaron Ramsey and Tottenham's Gareth Bale.
The pair have been in superb form during Wales' rejuvenation.
"They are incredible players," said Verheijen. "To be as young as they are and to have such a mature approach is amazing. They are very stable people. They are 21 or 22 but they play the game like 25-year-olds."