Brereton Diaz left Championship Blackburn at the end of last season and went to Villarreal in Spain.
The Chile international failed to score at all for the LaLiga side before joining Sheffield United on loan.
He made his debut as a substitute in the FA Cup clash against Gillingham, before starting against West Ham.
It was his first ever Premier League match and he took full advantage.
West Ham had taken the lead through Maxwel Cornet, before Brereton Diaz hit back.
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It was his first club goal since May, when he netted a double for Blackburn on the final day of the Championship season.
He penned a four-year deal with Villarreal, but things have not worked out there.
The forward has started just two LaLiga games, with a further 12 appearances from the bench, but did not score from the club.
Brereton Diaz signed on loan for the remainder of the 2023/24 season, and made an instant impact.