The no.60 LiveOn.com sposored Michael Shank Racing entry at the 2012 Rolex 24 at Daytona (Photo Credit: Rolex/Tom O'Neal)

The no.60 LiveOn.com sposored Michael Shank Racing entry at the 2012 Rolex 24 at Daytona (Photo Credit: Rolex/Tom O'Neal)

Two full course cautions in quick succession closed up the leaders of both classes at the 50th Rolex 24 at Daytona, setting up a tense finale to the event.

Thanks to Ryan Dalziel taking back his lap on track the top three overall were nose-to-tail at the front of the pack and quickly broke away as the slower Krohn Racing Lola delayed those behind. In consecutive laps Ozz Negri and Allan McNish both passed erstwhile leader Scott Pruett through the bus stop chicane though they failed to pull away from the Ganassi driver as just a second covered the top three DP cars after more than 20 hours of competition.

The field was bunched up again by another caution when the no.19 GP Porsche sailed into the tyre barriers on the infield at the end of a disasterous outbraking attempt. It was only lucky that it remained a single car incident as the errant Porsche went off, then cut back across the track at the apex of the next left hander.

The second caution lifted the no.6 Michael Shank Racing entry, driven by Gustavo Yacaman onto the lead lap, but the advantage was not to last long, the US open-wheel regular suffering a right-rear puncture. Yacaman successful brought the car back to the pits with limited damage but the delay dropped the car – Yacaman shares with Michael McDowell, Jorge Goncalves and Felipe Nasr – back to two laps off the lead and only a dozen seconds ahead of Scott Dixon in the fifth placed no.02 Ganassi entry.

From the second restart Pruett was unable to keep up with the pair of Ford powered Riley's ahead and Negri and McNish began their own battle for the lead. McNish pulled alongside several times, the most notable being as the pair rose up the banking around turn two of the formidable superspeedway. The pair came up behind a pair of GT cars – also side-by-side – only a quick move from McNish avoided contact as Negri sought a way through before the two leaders each decided to find their own way through the traffic result in a heart-stopping split second of four-wide racing around the 31-degree banking.

The two quick yellows had delivered the top five GT runners – three Porsches, a Ferrari and a Camaro – onto the lead lap.

Leh Keen held the lead for Brumos Racing before making a driver change stop to put pole position man Andrew Davis in the car. As a result the no.59 Porsche ended the hour third in class behind the Magnus Racing entry and TRG no.67

50th Rolex 24 at Daytona DP class standings after Hour 21

1. #60 Michael Shank Racing – Allmendinger/Negri/Pew/Wilson
2. #8 Starworks Motorsport – Dalziel/Luhr/McNish/Popow/Potolicchio
3. #01 Chip Ganassi Racing – Hand/Pruett/Rahal/Rojas
4. #6 Michael Shank Racing – Goncalves/McDowell/Nasr/Yacaman
5. #02 Chip Ganassi Racing – Dixon/Franchitt/McMurray/Montoya

50th Rolex 24 at Daytona GT class standings after Hour 21

1. #44 Magnus Racing – Lally/Lietz/Potter/Rast
2. #67 TRG – Bertheau/Bleekemolen/Goossens/Henzler/Pumpelly
3. #59 Brumos Racing – Davis/Haywwod/Keen/Lieb
4. #63 Risi Competizione – Beretta/Bertolini/Vilander
5. #57 Stevenson Motorsport – Bremer/Edwards/Liddell