UPDATE: The player has now been released under investigation.
The player, in his 20s, who cannot be named for legal reasons, was arrested at a nightclub in Brighton on Wednesday morning.
A man in his 40s was also arrested.
Sussex Police said in a statement:
"Two men have been arrested after a woman reported being sexually assaulted at a venue in Brighton, in the early hours of Wednesday (October 6).
"A man in his 40s and a man in his 20s, both from Brighton, were arrested on suspicion of sexual assault and remain in police custody at this time.
"The victim is receiving specialist support from officers."
A Brighton statement read:
"Brighton & Hove Albion are aware that one of its players is assisting police with the investigation of an alleged offence.
"The matter is subject to a legal process and the club is therefore unable to make further comment at this time."
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