Phillipe Coutinho has revealed that he is set to apply for the Portuguese nationality in order make a space for another non-EU players in Barcelona's squad.
The news provides a major boost for Ernesto Valverde's side with Mundo Deportivo reporting that it could pave the way for the La Liga giants to complete the proposed signing of Arthur Melo from Gremio.
Barcelona cannot registered Arthur or any other player from outside the European Union having already reached the three-player limit.
Liverpool star Coutinho, Brazil international Paulinho and Colombia's Yerry Mina make up the allocation.
But Coutinho could free-up one spot soon by obtaining Portuguese nationality through his wife Aine, having been married to her for more than the three years required to gain citizenship.
"Yes, I can get citizenship through my wife," he told Mundo Deportivo.
Uruguay international Luis Suarez has previously used the same loophole to gain Italian nationality through his wife Sofia Balbi.
Mundo Deportivo believe that the news could step-up Barcelona's ongoing pursuit of Arthur.
The 21-year-old midfielder has reportedly emerged as one of Valverde's top targets for the upcoming summer transfer window alongside Atletico Madrid forward Antoine Griezmann [Mundo Deportivo]
Last month, Mundo Deportivo claimed that the Barcelona were close to secure the services of the Brazil starlet from Gremio in a deal worth around €30m (£26.6m, $37m).
The Spanish publication then claimed that the Catalans knew they were unable to register him at but had still decided to step up negotiations in order to see off competition from other suitors, with Real Madrid, Chelsea and Paris-Saint Germain also keen.
Gremio president Romildo Bolzan said to UOL Esporte that negotiations between the clubs had stalled with the Brazilian publication claiming that they were asking the Catalans to increase their €30m offer as they only own 60% of Arthur's rights.
UOL Esporte added that the talks were expected to continue in the coming weeks but Bolzan made it clear that, even if they reach an agreement, Arthur won't move to the Nou Camp before at least the January transfer window of 2019.
"At this moment the [transfer talks] have stopped," Bolzan told UOL Esporte. "But I can tell you that Arthur will stay with us for another year [until December]. All parties agree on that. It's more or less agreed that Arthur will stay until the end of the year  if the deal is completed. I repeat, if it is completed."
Mundo Deportivo says that if Coutinho is awarded Portuguese nationality before the summer Barcelona could even consider trying to convince Gremio to bring the deal forward ahead of having Arthur ready for the start of the 2018-2019 campaign.