Mauricio Pochettino believes Dele Alli can be one of the world's best players as he predicted a decade of dominance for the highly-rated Tottenham midfielder.
An unheralded arrival from League One side MK Dons in January 2015, Alli has made a seamless transition to the Premier League, winning last season's PFA Young Player of the Year award.
The 20-year-old England international has scored six goals this campaign in his second season in the top flight and Tottenham manager Pochettino has backed Alli to enjoy continued success in London.
"Yes [he is a £50m player], why not? Today Dele Alli is showing a quality, a talent that it's difficult to find in Europe at 20 years old," said Pochettino, whose Tottenham face Watford on Sunday.
"There's no doubt he is and will be one of the best players in England in the next 10, 12 years. And England represents Europe, and maybe the world too.
"The Premier League is the toughest and best competition in the world, and if you are one of the best in England you are one of the best in Europe.
"In one year and a half we've talked a lot, and we can see how he is as a person, and that's important; how he's growing up, not only in football. For different reasons that crossed different problems, but he's improved a lot in his behaviour, in his game, in football.
"Now it's a big challenge for all the opponents to stop Dele Alli. He's said he wants success here, he's very happy here, and there's no doubt that he wants to win titles here."
Alli is under contract until 2022 and Pochettino added: "I am very honest in that situation. Sometimes he will joke in the dressing room or on the pitch, but he's very serious.
"Always I hear him say many times 'I want to succeed here, I want to win trophies here'."