Richard Westbrook and Michael Valiante reprised their victory in last year’s Sahlen’s Six Hours of The Glen in the No. 90 VisitFlorida.com Racing Corvette DP. With their victory today at Watkins Glen International, they became the first repeat Prototype winners of the 2015 TUDOR United SportsCar Championship.

Westbrook and Valiante previously won at Mazda Raceway Laguna Seca in May. The pair parlayed their win in today’s six-hour enduro into a five-point lead in the championship standings over rivals Joao Barbosa and Christian Fittipaldi, who finished third in the No. 5 Action Express Racing Corvette DP.

It was sun, rain, and rooster tails today at Watkins Glen International. Drivers and teams had to cope with constantly changing weather conditions that ranged from blue skies to deluges. The race pace was slowed by eight yellow flags, and stopped by a 14-minute red flag due to adverse weather conditions.

Westbrook and Valiante completed 160 laps on the historic 3.4-mile Watkins Glen circuit as the race finished under caution. Joey Hand and Scott Pruett were second in the No. 01 Ganassi Racing Ford EcoBoost Riley DP.

Westbrook started and finished the race, leading laps 16-29 and the final four circuits. He took the lead when Hand pitted for a splash of fuel with 10 minutes remaining. Seconds later, Kuno Wittmer crashed the No. 007 GTD Aston Martin on the pit straight and brought out the final yellow flag.

“The officials did a fantastic job with the red flag when the track was too wet and the yellows when there was standing water,” said Westbrook. “I couldn’t see a thing. When Joey pitted at the end, I just kept it off the walls and brought it home.”

“It was a tough race, and we knew we needed to stay out of trouble,” Valiante explained. “We had a windshield wiper failure and lost traction control, but everything fell right in the end.”

Hand’s machine had suffered damage to its left-front bodywork when race leader Ricky Taylor spun exiting Turn 10 on a late-race restart. The impact with the tire wall tore the front end off of Taylor’s No. 10 Konica Minolta Corvette DP and the car was retired after attempts to repair it proved futile. Hand also spun avoiding Taylor, but was able to continue.

“We ran dry, and I couldn’t have made another lap,” Hand revealed. “Our best chance was to try to build a gap. I like racing in the wet, we could really go for it.”

The GTLM class was another battle between factory-backed teams as eight different drivers led segments of the race and six cars finished on the lead lap.

The Porsche 911 RSRs were strong in the damp and drying conditions at the start, as Patrick Pilet came from fifth to first on the opening lap. The middle portions were dominated by BMW Team RLL’s Z4s and the Le Mans-winning No. 4 Corvette C7.R. But the BMW and Corvette bids came to naught as BMW driver John Edwards and Corvette ace Oliver Gavin both ended their races against the barriers.

In the end a pair of Porsches finished one-two in GTLM, with the No. 17 Porsche 911 RSR driven by Bryan Sellers and Wolf Henzler on the top step of the podium and the No. 912 Porsche North America Porsche 911 RSR driven by Jörg Bergmeister and Earl Bamber runner-up. Third place went to the No. 25 BMW Team RLL BMW Z4 GTE driven by Bill Auberlen and Dirk Werner.

The battle will be resumed north of the border at Canadian Tire Motorsports Park in Bowmanville, Ont. on July 12.