Online gaming company 888 Holdings has said it expects weak trading to be hit further by the World Cup as punters' attention turns to football.
It added that profit this year would be lower than previous expectations.
The group, which runs casino, poker and bingo websites, said its number of daily online poker players had dropped by 18% between January and May.
Unfavourable currency exchange rates were also having an adverse impact on trading, 888 said.
Hit by the weakness in the euro and sterling against the dollar, which is the company's reporting currency, 888 estimated that foreign exchange movements had cost it $5m so far this year.
"The board has revised its outlook for the remainder of the year and now expects profit to be significantly lower than previous market expectations," the company said in a statement.
Shares in 888 closed down 20.8% at 53.25p on Friday.