This race had been one of the most important sportscar racing venue in the US when it was litterally dropped of the World Sportscar Championship. The main reason for this fact was that the track was no longer eligible for a round of the WSC because of the track state. It needed extensive repairs to be again eligible for the WSC and it was never to be. So IMSA took the challenge and decided to include this race in their schedule. Alec Ulman himself wished the new organisation good luck when the 1973 event was launched for the first time by IMSA. Of course, the field was far away from those seen before at Sebring but it was nonetheless an extremely high quality field of GT machinery. 72 cars took the start of the first IMSA sanctioned Sebring race. It looked like the Corvettes would have to win the race and they really could have done it! They led the race until lap 86, Tony de Lorenzo-Steve Durst fighting off with Dave Heinz-Jerry Thompson. But they both experienced problems which led them to a retirement later in the race. The lead was soon to be taken by the ever consistent Peter Gregg-Hurley Haywood who were fighting hard with the other Porsche Carrera driven by Michael Keyser-Milt Minter. They managed to win the race with a one lap margin victory over their closest follower. Third in the race were Ron Grable-John Greenwood-Michael Brockman who finally broke the German streak with their Corvette. 41 cars were still running at the chequered. The GTU class was taken by the Porsche 911S driven by Steve Behr-Don Lindley-Brian Goellnicht who placed 7th overall.
The 12 Hours of Sebring were quietly on the way back to a new recognition by the fans and later by the media.