Barcelona's 'gift' to Atletico Madrid back in 2013 came in the form of David Villa, and the favour could be returned by Simeone's team.
Villa's transfer agreement, which was quite favourable for the Madrid team, included a clause which gave Barcelona the right of inquiry over Saul Ñiguez.
Back then, the footballer was relatively unknown, but today his value increases with every passing moment and Europe's top clubs have registered an interest in signing the skillful playmaker.
It seems unlikely that Atletico will let him leave, especially due to the transfer ban imposed by FIFA, but Barcelona remain attentive of a player who they like and is shining in the under-21 European Championships.
In the meantime, Saul and his agent Jorge Mendes are looking to improve his current contract, with a deal that could see him stay at the club until 2022, or even 2024.