A Brighton player tested positive for coronavirus, confirmed club chief executive Paul Barber.
Three unidentified members of Albion's team underwent tests after showing symptoms of Covid-19, and one tested positive.
"We have tested three players, one has tested positive. We are not routinely testing them, we are only testing them when symptoms arise," Barber said during a press conference hosted by video link.
"But the one who tested positive was today, so it's unfortunate, but he's fine and he's obviously getting the attention he needs right now."
Meanwhile, Brighton and fellow Premier League club Bournemouth have guaranteed a minimum of 1,000 tickets for frontline NHS staff to attend future matches.