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Sheffield United said it will support striker David McGoldrick after he was racially abused on social media.
The club shared an image from McGoldrick's Instagram account showing the abuse, with the Blades player writing "2020 and this is life".
"This cannot continue", wrote the club. "Something needs to change".
McGoldrick scored his first Premier League goals as United beat Chelsea 3-0 at Bramall Lane on Sunday to move into the Premier League's top six.
Republic of Ireland striker McGoldrick's abuse follows the arrest of a 12-year-old boy in connection with racist messages sent to Crystal Palace forward Wilfried Zaha on social media.
Players in England's top flight have been kneeling in support of the Black Lives Matter movement before every match since the season restarted in June.
Sheffield United added: "As a club we will support David McGoldrick and will do all we can to find the perpetrator of this disgusting message.
"We will work with the relevant authorities to ensure the person behind this post is brought to justice."
The Football Association of Ireland condemned the "appalling" abuse and offered its support to McGoldrick, who made his international debut in 2014.
A spokesperson added: "Such behaviour is appalling and cannot be tolerated by football or society."
South Yorkshire Police said it is in contact with Sheffield United and "will continue to work with the club in relation with this matter."