A 16-year-old boy has been arrested for allegedly calling Huddersfield Town midfielder Philip Billing a "black donkey" online.
Billing, 22, tweeted a private message he had been sent on Instagram, with a 'thumbs down' emoji.
In the expletive-ridden message, Billing, a Denmark international of Nigerian descent, was told to "leave our club".
West Yorkshire Police confirmed the arrest was made on Wednesday morning.
"I never want to see you in a Town kit ever again, you useless wannabe black donkey," the message said.
A police statement read: "Following a report received by West Yorkshire Police this morning (13 March) in relation to abusive racial comments on social media, police have now arrested a 16-year-old male.
"The teenager has been arrested on suspicion of malicious communications and is being investigated as a hate crime. Enquiries remain ongoing.
"Kirklees District Police would like to reassure the public that this incident has been swiftly and proportionately investigated.
"All reports of hate incidents are taken extremely seriously by West Yorkshire Police and all such reports will be thoroughly investigated."
Huddersfield said in a statement that the club "does not tolerate abuse of any kind and has a zero-tolerance stance towards any form of discrimination".
It added: "We will give our full co-operation to the police to deal with this matter in the strongest possible way."
Kick It Out said in a statement: "We condemn the disgraceful abuse that Philip Billing has received online and call on social media companies to take steps to act against people who use their platforms to carry it out.
"Recent events underline that players should be protected from abuse both on and off the pitch. We are liaising with Huddersfield Town and have offered our support to Philip."
Billing, who was named youth player of the season in 2016, joined the Terriers in 2014 and has made 74 senior appearances for the club.
Huddersfield are bottom of the Premier League, 16 points from safety, having won just three games all season.