Sergio Diaz
Diaz favours move to Serie A over the Premier League, says his father.Getty

Paraguayan starlet Sergio Diaz will agree to join Roma after receiving an offer that was 'more concrete' than the one put forward by Chelsea.

Chelsea have been keen to add the 17-year-old Cerro Porteno striker to their ever-growing pool of young prospects and even took the step of inviting his father to Stamford Bridge for their final game of the season against Sunderland in hopes of swaying him, reports suggested.

But it would appear Roma are now on the brink of securing a deal that could cost the Serie A side as much as €8m, after the youngster's father Ismael Diaz revealed his son has already made up his mind on his future.

"My son wants to play for Roma," Ismael Diaz told LaRoma 24. "In fact, their offer is more concrete than Chelsea's."

Diaz, who made his first team debut for Cerro Porteno at the age of 15, does not turn 18 until March 2016, meaning he will have to wait until next summer before he can complete his move to the Giallorossi.

Chelsea have already scoured South America in recent months in their attempts to unearth the latest talents. The Blues have already secured the services of Brazil Under-20 international Nathan, who will officially join the club from Atletico Paranaense on 1 July having agreed terms and passed a medical.

The midfielder announced the move himself via his Instagram account, writing: Thank you Chelsea for trusting in me, I will do my best to support my team on reaching new achievements. WE ARE ALL BLUE."

Jose Mourinho has confirmed the club already plan to send the Brazilian youngster out on loan next season.