It happened during the Girona match (I think), but Villarreal announced an ‘agreement for the transfer’ of Nahuel Leiva to Olympiacos. It would appear the deal is a sale with a purchase option retained, though no fianancial details have been forthcoming.
Matiás Nahuel Leiva joined Villarreal’s youth setup in 2010 at age 14, moving from his native Argentina. He made his La Liga debut in January 2014, but while he impressed at the B team level, success at the first team level eluded him. He was a member of Spain’s under-19 team that won the 2015 U-19 Euro championship, scoring a couple of goals in the process.
Transfermarkt had him as a €4m value (at age 19) when he was sent to Real Betis, but that’s down to just €1m now, which is a reflection of his lack of progress over the last couple of years.
Nahuel at his best can be a tricky left winger who can score some himself as well as create chances for others—hopefully he will do well in Greece. Good luck to him!