Rolex 24 Hour 6: Brumos Porsche leads

Problems suddenly struck two leading Daytona Prototype contenders. AJ Allmendinger was leading the race on lap 155 when his race-leading No. 6 Michael Shank Racing Ford Riley slowed to a stop in the infield – leading to that car's retirement. Then, the third-place No. 76 Krohn Racing Ford Lola suddenly lost power, with the team looking for the cause of the problem.

Just before the six-hour mark, defending race winner Memo Rojas hit a curb, sending the No. 01 TELMEX/Target Chip Ganassi Racing with Felix Sabates Lexus Riley to the garage. The team lost one lap making repairs, putting Rojas in 10th position, the first car one lap down.

At six hours, Buddy Rice led in the No. 58 Brumos Porsche Riley, followed by Scott Dixon in the No. 02 Chip Ganassi Racing with Felix Sabates, Christophy Bouchot in the No. 55 Supercar Life BMW Riley and Hurley Haywood in the No. 59 Brumos Porsche Riley.

In GT, Jan Magnussen led in the No. 07 Banner Racing Pontiac GXP.R followed by Richard Westbrook in the No. 87 Farnbacher Loles Porsche 997.

AJ Allmendinger: "I think, unfortunately, something in the motor suddenly popped. A sense down inside suddenly failed and that triggered it. The motor didn't blow or anything, but it would be a four-hour process to get down to that sensor and change it. Unfortunately, by the time we did that, there would be no point being out there. I feel bad for Michael Shank Racing and for Michael himself – they put their heart and soul into this. They want it as bad as I do. I thought last year's car was the best car I've driven, but this year's car – by far – was better. I was doing about 85 percent out there – I had at least another second in the car. One of those breaks. That's the good and the bad about the Rolex 24. I guess if something's going to happen, it's good to go out on top. I'll be back next year.

Nic Jonsson: "We're not exactly sure what happened yet. Darren (Turner) was out there, running very strongly, and all of a sudden, the engine just stopped – just like the 6 car. They're trying to find out exactly what it was."

Hour 6 Standings (1/4 point)