Bet365 will continue to support the Charlie Hall Chase for a further three years, up to and including the 2008 renewal.
The online bookmaker first sponsored the Grade Two contest in 2003 when the Howard Johnson-trained Ballybough Rasher caused a 40-1 shock with a defeat of favourite Marlborough.
Saturday’s Charlie Hall Chase is worth £75,000 (€110,000) and has attracted a suitably high-class entry including last year’s winner Grey Abbey, Cheltenham Gold Cup runner-up Take The Stand, Kingscliff, Ollie Magern and Keen Leader.
Bet365 chief executive John Coates said: “We are thrilled with the success of the first two years of our sponsorship.
“It was a joy to see Grey Abbey win the Charlie Hall Chase last year and very satisfying to watch him emerge as the best staying chaser in Britain.
“This season’s race looks like being our best yet and we look forward to continuing our partnership with Wetherby over the next three years.”
Chief executive of Wetherby racecourse James Sanderson added: “We are delighted that bet365 is extending its commitment to the bet365 Charlie Hall Chase, which is part of the BHB’s Order of Merit.
“Bet365’s continued support will ensure that the race maintains its standing as a prestigious early season prize for the country’s leading chasers.”