The Argentine left the club in January for Italian side Fiorentina.
Fiorentina's Mauro Zarate in action with Tottenham's Tom Carroll
Tonight should be an historic occasion for West Ham United as they play their first ever game at the London Stadium.
Better known as the Olympic Stadium, the club have moved from their beloved Boleyn Ground to their new home and will christen it this evening as they take on NK Domzale in the second leg of a Europa League qualifying clash.
Plenty of the West Ham players have taken to Twitter or Instagram to show off their excitement at playing in this momentous fixture.
But even a player whose stay at West Ham was brief has also been in on the action.
Argentine forward Mauro Zarate sent this message on Instagram earlier today, wishing his old team the best of luck:
Zarate spent just 18 months at West Ham. He was frozen out under Sam Allardyce but made more of an impact under Slaven Bilic before a move to Italian side Fiorentina in January.
(From L-R) West Ham's Angelo Ogbonna, Reece Oxford, Manuel Lanzini, Diego Poyet and Mauro Zarate (R) during training
Despite his difficulties at the club he always had a good relationship with the West Ham fans and he is clearly excited for them this evening.
Zarate will be amongst those hoping that West Ham can overcome the 2-1 deficit from the first leg and make it a memorable night for the right reasons.