José Mourinho personally assured Marco van Ginkel that he would be granted significant first-team football with Chelsea to convince the Holland international to swap Vitesse Arnhem for the Premier League, with the young midfielder completing a £9m move to Stamford Bridge on Friday.

Van Ginkel, who made his senior international debut against Germany last November, was a key member of the Vitesse side who finished fourth in the Eredivisie last season, their highest placing since 1998, and was voted the best young player in the Netherlands at the end of the campaign. Ajax declared an interest in taking him to Amsterdam earlier this summer and the 20-year-old's instinct was to make that step up before seeking a move at an elite club in either England or Spain.

Indeed, the Dutch champions believed they were close to securing his services with the promise of an integral role in their lineup. "Van Ginkel is a great young talent and we would have liked him to come to Ajax," said Marc Overmars, who is now sporting director at the Amsterdam ArenA club. "Whether it is too early for him to go to Chelsea or not, I don't know. With us, he would have played a lot of games and played in the Champions League."

But Mourinho spoke with the player and, much to Ajax's disappointment, convinced the youngster he would feature regularly rather than following the likes of other recent signings, such as Kevin de Bruyne and Romelu Lukaku, by continuing their development on loan elsewhere. The Portuguese considers Van Ginkel as the long-term successor to Frank Lampard in Chelsea's midfield and hopes he can learn from the veteran, who signed a one-year contract extension at the club back in May, within the senior set-up.

Chelsea were always favourites to secure Van Ginkel – Manchester United were among a number of other clubs who had also tracked the player – as a result of their close relationship with Vitesse, born of the friendship between Roman Abramovich and the Dutch club's Georgian owner, Merab Jordania. The likes of Tomas Kalas, Patrick van Aanholt, Gaël Kakuta and Nemanja Matic have spent time on loan in Arnhem, with the Londoners having watched Van Ginkel's progress with interest from afar. The midfielder joined Vitesse at the age of seven in 1999 and progressed through the youth ranks before making his Eredivisie debut at 17.

He hopes to feature at the World Cup finals in Brazil, but to do that he must make an impact in the Chelsea first-team. Mourinho is confident he can be integrated: the player is comfortable in the 4-3-3 system the manager intends to implement, and boasts the physique and box-to-box energy and eye for goal that have drawn the inevitable comparisons with Lampard. He scored eight goals in 33 appearances last season.

Another Dutch youngster, the centre-back Jeffrey Bruma, has seen his £2.5m move from Chelsea to PSV Eindhoven stall after medical tests revealed he is suffering from a heart problem. The 21-year-old, who has spent the last two years on loan at Hamburg in the Bundesliga, will undergo further examinations and is still hopeful a deal can be completed to return to his homeland on a four-year contract.