Trevor Bayne, who celebrated his 20th birthday the day before, became the youngest winner of the Daytona 500 today when he held off a hard-charging Carl Edwards to win the 53d annual Great American Race in a thrilling green-white-checkered finish at Daytona International Speedway.

Driving the legendary No. 21 Motorcraft Ford fielded by the Wood Brothers Racing team, Bayne, of Knoxville, Tenn., recorded his biggest victory of his NASCAR career in only his second career start in a race in which track records were set for 74 lead changes among 22 drivers and 16 cautions.

``This is incredible; our first 500? Are you kidding me?' Bayne said in Victory Lane. ``It's unbelievable.'

Bayne went into the lead when David Ragan was shown the black flag after green-white-checkered on lap 202 was aborted by a four-car melee on the backstretch that collected car of Dale Earnhardt Jr.

NASCAR officials dealt Ragan a huge blow when they showed him the black flag for passing under caution before taking the green. TV replays showed Ragan leaving his lane to jump in front of Trevor Bayne, Ragan's drafting partner.

Bayne inherited the lead on the second attempt at a green-white-checkered start on lap 206 and remained there with the drafting help of Bobby Labonte. When Edwards came steaming up from behind on the inside of the final corner, Bayne shut the door with a smooth move to the inside that sealed the victory.