Sunny's move to Portsmouth looks to have collapsed, skysports.com understands.
The midfielder is currently on a season-long loan at Osasuna from Valencia.
The 20-year-old underwent a medical on the South Coast on Wednesday, but discussions with the club are believed to have broken down over finances.
Pompey were keen to bring the highly-rated Spanish youth international to the club.
However, it now appears that the deal has floundered and that Sunny will be heading back to Spain for the rest of the season.