Reigning Nascar champion Tony Stewart has won just about every race held at the Daytona International Speedway - except for the one that really counts. The Daytona 500 - and it's today.Later today he will be giving The Great American Race another shot and be up against Carl Edwards, with whom he tussled for the Sprint Cup title until the final rounds of the last race of the season, and who will start on pole.The 500, the grand opening to the Nascar season but almost a championship in itself, has extra interest this year given the involvement of Danica Patrick, who switched from open-wheel Indy racing to become the third female to race in the 500. Forty-three of the top drivers in the world will be on the grid for Nascar's biggest, richest and most prestigious motorsport event. 'WE'RE NOT JINXED'Only a Patrick victory, or perhaps a long-awaited triumph for 53-year-old Mark Martin, would cause more of a stir than Stewart finally gaining glory in the one big title that has eluded him"I don't think we feel jinxed. We've had some really good cars here and we've just missed," Stewart, who was second in 2004 and third in 2008, said this week. "We've been leading late in these races and so I feel like (with) the law of averages, we're going to get one eventually."Stewart, with three Daytona wins in the 400-mile (640km) race, is a racing obsessive who drives on short circuits during Nascar's off season, something he tries to squeeze into his programme throughout the year.The 40-year-old has three Sprint Cups to his name as well as, in open-wheel competition, the 1997 Indy Racing League championship, but it clearly grates him that he has yet to win the big one."It's not a good feeling not to have that tally in the win column. Everything else we have pretty much accomplished in this sport that we want to accomplish," he said. "It's the biggest race of the year; everyone wants to win that race. I won't say it's not a complete career if you don't win it, but there is a lot of priority on this."INTERNATIONAL APPEALBut the 500 mile (800km) race, with plenty of risk of crashes and many lead changes, often produces a surprise - last year rookie Trevor Bayne won in his second Sprint Cup start. Edwards, also winless in the 500, is certainly among the favorites - as is Jimmie Johnson, smarting from the end of his run of five straight Sprint Cup titles and with the experience of victory at Daytona in 2006.Jeff Gordon, a three-times winner, will be keen to prove he is not a fading force, and there is always a special level of support for Dale Earnhardt Jr. at Daytona, the site of his father's death in the 2001 race.While Nascar remains an almost exclusively American passion, there is international interest in the 500 with Australian Marcus Ambrose and Colombian ex-Formula 1 driver Juan Pablo Montoya both in the hunt.