DAYTONA BEACH, Florida — Joe Gibbs Racing teammates Matt Kenseth and Denny Hamlin surged into the roles of favorites for the Daytona 500 Sunday after roaring to victories in preliminary races at Daytona Speedway. While Kenseth and Hamlin claimed the spotlight in their Toyotas, concerns grew that the Speedway could be turned into a collision course in NASCAR's season-opening spectacular as pack-racing has led to crashes that have wrecked 20 cars this week. Kenseth, a two-time winner at the 2.5-mile, high-banked oval, won his preliminary 150-mile race on Thursday, holding off Kevin Harvick and Kasey Kahne. In 2012, Kenseth went on to win the Daytona 500 after winning his qualifying race. Hamlin, who missed most of 2013 due to a back injury, not only won his crash-marred qualifying race but also won a race on the track last Saturday. Garage insiders consider the preliminary events good indicators for the 56th edition of the event known as the Great American Race. Under unique race rules, only the front row of pole winner Austin Dillon and Martin Truex Jr. had been locked into their starting positions before the qualifying races. However, Truex wrecked his car in the qualifier, sending him to the rear of the 43-car grid in his back-up car when they start Sunday. Kenseth starts third and Hamlin fourth in the second row. Despite the impressive showing, team owner Gibbs, the former three-time winning Super Bowl coach of the Washington Redskins, was not overconfident about seeing one of his cars win Daytona for the first time since 1993 with Dale Jarrett. “It shows you what a tough race this is, the 500,” said Gibbs. “We won once. Probably one of the greatest sporting experiences I've ever had. I was thrilled.” Multi-car accidents in a preliminary NASCAR race last week, in one of Thursday's qualifying races and in practice for Sunday's Daytona 500 suggest the 56th edition of the event could produce one of the wildest races in years. To keep the race cars under 200 mph at Daytona and also at Talladega, NASCAR requires cars use a device called a restrictor plate that reduces engine horsepower. The reduction has resulted in cars bunching up in huge packs, running door handle to door handle at speeds over 190 mph. When something goes wrong, it results in a high-speed domino effect accident. Last week, in a preliminary race involving only 18 cars, virtually half the field was wiped out in one incident. In practice Wednesday, a four-car accident was followed later by a seven-car incident, which shut down practice early. — Reuters