Argentine Vietto has somewhat of a breakthrough season in La Liga, having joined Villarreal last summer from Argentine side Racing Club.
He has since scored over 20 goals in all competitions and helped the Spanish side to a Europa League last-16 place.
His form has caught the attention of potential suitors Liverpool, who were extremely keen and had labelled him as their number one target this summer, whilst Arsenal and Atletico Madrid have also been interested.
And, claims in England now state that both English clubs have triggered his £14.2m release clause.
The fee was originally reported to be £30m, but it is understood that a lower fee is now available after Villarreal failed to qualify for the Champions League.
Atletico Madrid are also considering a summer move, but it seems the Argentine will now decide on which English side to join.