William Hill warned that its full-year retail profits will be lower than expected after sporting results went against it in the first half and punters stayed away from its high street shops.
The bookmaker cited poor football results in May when the big four clubs, Manchester United, Liverpool, Chelsea and Arsenal kept winning, as well as unfavourable horse racing results in March and the cancellation of meetings earlier in the year, for a 1 per cent drop in retail revenues to £393.2m for the six months to 30 June.
Ralph Topping, the chief executive of William Hill, said he would wait until several weeks into the new football season before making any forecasts about consumers cutting back on gambling during the recession.
"Football does bring people into betting shops and we expect a lot of interest this season now there is a fifth force in Manchester City," he said.
Over the half-year, William Hill's pre-tax profit fell to £91.5m from £111.1m, the year before. Mr Topping said: "As a consequence of the first-half performance, the difficult July and the uncertain economic environment, we anticipate that our profits for the full year from the retail channel are likely to be lower than expected."
Its total revenues rose by 5 per cent to £515.5m. William Hill's online revenues jumped by 58 per cent to £100.1m, boosted by its acquisition of Playtech, which operates gaming sites, in December.
Mr Topping said he had "big concerns" about the way the horse racing industry is being run, particularly the shifting of key races such as the Derby to a Saturday when it has to compete with football's World Cup and European Championships every two years.
William Hill Online said it is moving its online betting service, Sportsbook, and online fixed-odds games from the UK to Gibraltar to save costs.