Agent Cristian Zaccardo admits Premier League clubs threatened to beat Napoli to the signing of Khvicha Kvaratskhelia last summer.
The Georgia winger had been a long-term target for Tottenham and Everton, but eventually joined Napoli.
World Cup winner Zaccardo told La Gazzetta dello Sport: "I was wrong: I had predicted that Kvaratskhelia in two years would cost 50 million (euros).
"Instead I know that one year is enough ... Napoli was skilful and timely: there was a risk that the Premier League would set its sights on Khvicha, who has also been in evidence for at least a couple of years with the Georgian national team."
Zaccardo says Napoli coach Luciano Spalletti is ideal for the winger: "Exactly. Perfect choice. Also because Spalletti is the best guide for Kvara: he also speaks a little Russian ..."