A pre-contract agreement between club and play was agreed in January, and Pasalic - who has been compared to Chelsea legends Frank Lampard and Michael Ballack - is set to finalise the deal soon - with a medical planned for the end of May.
Whilst any number of 19-year old players would consider a move to a club of Chelsea's stature a highlight of their season, Pasalic has received even more good news in the last few days, with international head coach Niko Kovac including him in the preliminary 30-man squad for the Brazil World Cup.
The 6'1" box-to-box midfielder is being touted as an excellent auxiliary player, able to provide strength and energy alongside the more creative Luka Modric and Ivan Rakitic. Whilst only having proven himself in the Prva HNL - a mediocre league when compared to European standards - there were strong calls for Pasalic's inclusion, and Kovac has accepted that the midfielder's skills could potentially be key to any success that Croatia may find in Brazil.
Although only included in the 30-man preliminary squad, Pasalic has the pre-tournament training camp to prove himself to his coach and teammates, and to secure his place in the 23-man Finals squad. The final deadline for the 23-man squad is 2 June, and Chelsea officials must be delighted that they have secured the starlets services before he can announce himself on the world stage.
The full 30-man preliminary squad is as follows.
Goalkeepers: Stipe Pletikosa, Danijel Subasic, Oliver Zelenika
Defenders: Darijo Srna, Dejan Lovren, Vedran Corluka, Gordon Schildenfeld, Danijel Pranjic, Ivan Strinic, Domagoj Vida, Sime Vrsaljko, Igor Bubnjic
Midfielders: Luka Modric, Ivan Rakitic, Niko Kranjcar, Ognjen Vukojevic, Ivan Perisic, Mateo Kovacic, Milan Badelj, Ivo Ilicevic, Marcelo Brozovic, Ivan Mocinic, Mario Pasalic, Sammir
Forwards: Mario Mandzukic, Ivica Olic, Eduardo da Silva, Nikica Jelavic, Ante Rebic, Duje Cop
Croatia are in Group A, alongside tournament hosts Brazil, Mexico and Cameroon.