Wolverhampton Wanderers and Sunderland said they were appalled by the racial abuse directed at their players on social media on Sunday following defeats in the Premier League.
Wolves striker Tolu Arokodare and Sunderland winger Romaine Mundle both received online abuse, with the incidents coming less than 24 hours after Wesley Fofana and Hannibal Mejbri were racially abused following Chelsea's draw with Burnley.
Wolves said they were disgusted by the multiple instances of abuse received by Arokodare following their 1-0 defeat by Crystal Palace.
"We stand firmly alongside him, and alongside all footballers who are forced to endure this abuse from anonymous accounts acting with apparent impunity," the club said in a statement.
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Sunderland, who lost 3-1 to Fulham, said they were working with the authorities to identify those responsible for the messages targeting Mundle.
"The abhorrent behaviour displayed by multiple individuals is unacceptable and will not be tolerated by the Club under any circumstances," Sunderland wrote on their website.