Wales already boast one of world football's hottest properties in Gareth Bale, who Coleman joked could be shunted from the headlines by 19-year-old Williams when their next qualifier comes around in September.
"In the next couple of trips you will be asking me about Johnny as much as you do about Gareth," said Coleman.
"He will go to another level and you can see why everyone is so excited. He's still got a lot of work to do but he's certainly a gifted player."
The diminutive midfielder, who plays in the second tier of English football with south London club Crystal Palace, is nicknamed 'Joniesta' in reference to Barcelona and Spain's phenomenal playmaker Andres Iniesta.
Despite his fine performance in his second international, Williams could not stop Wales slipping 10 points behind Group A pacesetters Belgium and Croatia.
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