The GT1 and GT2 classes will provide nonstop action at the Mobil 1 Twelve Hours of Sebring. Braselton, Ga. - March Madness? Yes, we have it. It's the annual rite of spring when sports car racing's best descend on central Florida for the Mobil 1 Twelve Hours of Sebring. This year's 54th running marks the opening of the 2006 American Le Mans Series season, one that promises to be the Series' most competitive and compelling since it was formed in 1999.

There hasn't been an American Le Mans Series race with more compelling storylines than next week's 12-hour endurance classic. In all four competitive sports car classes there are plots, subplots and nuggets. Here are some relating to GT1 and GT2.

GT2: VARIETY IS THE SPICE

After seeing its drivers and teams win GT2 from 2002-05, Porsche faces its toughest challenge yet in 2006. Eight Porsche 911 GT3 RSRs will be on the grid at Sebring, led by Series championship contenders Petersen Motorsports/White Lightning Racing, Alex Job Racing and Flying Lizard Motorsports; that's the order they finished in the 2005 team championship. Other GT2 teams fielding Porsches at Sebring include J3 Racing (a runner-up at Sebring last year), Farnbacher Loles Racing and Vonka Racing.

Porsche is unbeaten in class at Sebring since the Series' formation. Last season the No. 31 Petersen/White Lightning Porsche of Jorg Bergmeister, Patrick Long and Lucas Luhr outlasted the rest of the field for class honors. Some of the names for 2006 are different, but that doesn't diminish the expectations Porsche has for an eighth straight class win.

Porsche and Panoz will be joined at Sebring by other elite GT2 manufacturers BMW, Ferrari and Spyker. Standing in the way is a field full of entries representing the world's most prestigious manufacturers: Panoz, BMW, Ferrari and Spyker.

"This probably is going to be the strongest GT2 field I've seen in the Series," said Gunnar Jeannette, a driver for Multimatic Motorsports Team Panoz who is teaming with Tom Milner Jr. and Champ Car star Bruno Junqueira. "It's shaping up to be a great year for competition. I think it definitely will be the class to watch."

Multimatic Motorsports Team Panoz will field two Panoz Esperante GTLMs for Sebring and the full American Le Mans Series season. The Canadian team has taken over the development and competition aspects of the Panoz operation, and the results were overwhelmingly positive at the Series' Winter Test in January. Scott Maxwell posted the fastest time of the three-day session among all GT2 cars.

Team LNT, one of the most successful GT racing programs in Europe, also will field a Panoz Esperante GTLM at Sebring. It marks the race debut of the Esperante under the Team LNT banner with hopes of campaigning in several series in Europe and the 24 Hours of Le Mans.

Also new (in a way) is BMW Team PTG, which is back in the American Le Mans Series for the first time since 2003. Winner of the first Series GT team championship in 1999, BMW Team PTG will compete at Sebring and the full Series season with two BMW M3s. Both cars were at January's Winter Test where the team showed that it doesn't plan on missing a beat in its Series return.

"As a driver, it's fantastic," said Bill Auberlen, who will partner with Joey Hand and Ian James. "To come back into the American Le Mans Series with the BMW M3 is the best thing you can do in racing. I had so much success with Tom (Milner) and PTG. Then to reincarnate that relationship with Yokohama is a tremendous positive. This thing is going to be a winning program."

Ferrari and Risi Competizione also are back in GT2 after a one-year absence. The Risi team will field a new Ferrari F430 GTC at Sebring, with a second car competing at select Series events. It was a Risi Ferrari that ended Porsche's 21-race class winning streak at Lime Rock two years ago. Ferrari has a rich history of success in the American Le Mans Series with six class victories.

"This new car looks promising," said team owner Giuseppe Risi said. "Intense chassis development has resulted in increased stiffness, and the car features a new increased displacement engine design with more horsepower. I look forward to joining the battle with a stellar list of GT2 competitors, including Porsche, BMW and Lexus. The competition will be great for everyone-manufacturers, teams, drivers, fans, everyone."

In addition, Spyker Squadron will return to Sebring with two Spyker C8 Spyders.

The GT1 battle between Corvette Racing and Aston Martin Racing will resume at the Mobil 1 Twelve Hours of Sebring GT1: THE REMATCH IS JOINED

Last year's GT1 class race at Sebring was one of the most talked about and historic finishes in American Le Mans Series history. Aston Martin won its class in its first appearance at Sebring since 1983 with a stunning victory over the two-car Corvette Racing squad.

As in 2005, Aston Martin Racing will enter two DBR9s at Sebring with a lineup that includes drivers from last season (Darren Turner, Tomas Enge, Pedro Lamy and Stephane Sarrazin) and a couple of newcomers (Nicolas Kiesa and Jason Bright).

"Last year our performance at Sebring far exceeded our expectations but we're not underestimating the challenge this time, especially from the factory Corvette team," said Aston Martin Racing Team Principal George Howard-Chappell. "I've no doubt it's going to be a very tough race but I've every confidence that our drivers will give us the best possible chance of a good result."

Aston Martin Racing and Corvette Racing went head-to-head four times last year: Sebring, Le Mans, Petit Le Mans and the Monterey Sports Car Championships. Corvette Racing, with its Corvette C6-Rs, won the latter three to earn a bit of revenge from Sebring.

"Personally I like the hype," said Corvette Racing's Johnny O'Connell, who will team with Ron Fellows and Max Papis at Sebring. "This is really the best of the best: Europe's best taking on America's best. Both teams are very strong and hungry. The fans I know are in for a treat."

Corvette Racing also enters with five straight season team championships, and No. 4 mates Oliver Gavin and Olivier Beretta won the class drivers title in 2005. As was the case in 2005 and 2004, Jan Magnussen will join the two Ollies at Sebring, Le Mans and Petit Le Mans.

It's not a two-team battle though. Konrad Motorsports is returning to the Series with two Saleen S7Rs that are no strangers to Aston Martin and Corvette. Tom Weickardt, after campaigning a Dodge Viper from 2001-05, will drive one car with other drivers to be announced. Italian Paolo Ruberti, who has driven Saleens in the FIA GT Championship in the past two seasons, will drive the other Konrad Saleen along with two other yet-to-be-named partners.

The American Le Mans Series begins its 2006 season with the 54th Mobil 1 Twelve Hours of Sebring. The 12-hour endurance classic is scheduled for 10:30 a.m. EST on March 18 at Sebring International Raceway. It will be televised live on SPEED Channel in North America and MotorsTV in Europe. In addition, Greenlight-Television will distribute the race worldwide to more than 510 million households. American Le Mans Radio will have flag-to-flag coverage available at www.americanlemans.com, along with IMSA Live Timing & Scoring.