The Grand-Am Rolex Series' busiest stretch of the season concludes this weekend at Watkins Glen International with its second-longest race of the year. The fourth race in five weekends, and eighth of 13 on the 2012 calendar, is the Sahlen's Six Hours at the Glen – also the second round of Grand-Am's new three-race North American Endurance Championship.

A week ago at Road America, Scott Pruett and Memo Rojas took Telmex Chip Ganassi Racing with Felix Sabates to their first win of the season. It came with a bit of luck; the Riley-BMW took the lead when Ricky Taylor crashed out under yellow in the SunTrust Racing Corvette. The challenge for BMW continues to be matching the Corvettes on outright pace; Pruett told RACER.com earlier this week the car still appears slightly down on power, despite a rev boost increase for the BMW and Ford powerplants in advance of Road America.

Nevertheless, Pruett and Rojas have been the model of consistency with five podiums in the last six races, and currently lead the overall championship by five points over Starworks' duo of Ryan Dalziel and Enzo Potolicchio. The globe-trotting pair for Peter Baron's squad have won two of the three FIA World Endurance Championship races in LMP2 – the 12 Hours of Sebring and 24 Hours of Le Mans – and seek their first Grand-Am win of the year this weekend.

“It really has been an unbelievable season for us, but I don't think it's maybe a surprise to us,” Dalziel said. “We feel over the past couple of years we have put together a really strong team, and we definitely going into this season, partnering up with Enzo and myself and the great people at Starworks, they expect great things and to be in the hunt for the championship.

“We feel that what we are doing in the WEC has been very special and brings awareness to a little competition in Grand-Am. We don't dominate in Grand-Am by any means. We consider ourselves a front-runner but I think the performances we have put on in the WEC have opened people's eyes and the world to just how difficult Grand-Am is.”

There have been five winners in seven races from four different teams. Ganassi joins Corvette squads Spirit of Daytona (with two different driver pairings), SunTrust, Action Express and Daytona winners Michael Shank Racing. With that win in the Rolex 24, MSR enters the Glen as leaders in the NAEC points – which will be awarded at half distance and the checkered flag this weekend. Teams can earn a maximum of 20 and minimum of eight NAEC points.

Besides the usual nine DPs, some guest drivers come back including former Champ Car archrivals Sebastien Bourdais (alongside Dalziel/Potolicchio at Starworks) and Paul Tracy (Doran Dallara-Ford) and Corvette Racing factory driver Oliver Gavin (alongside Antonio Garcia, Richard Westbrook at Spirit of Daytona).

GT has seen Ferrari largely entrenched at the front of the field with the new 458 Grand-Am. AIM Autosport Team FXDD's Jeff Segal and Emil Assentato, with three victories, lead the standings by 21 points over Stevenson Motorsports' Robin Liddell. By contrast, DP's gap between the top six driver/team combinations is just 15 points!

Liddell's Camaro has been a toss-up in co-drivers; primarily John Edwards, but otherwise Ronnie Bremer with Edwards' injury earlier this year. The team has yet to win but ranks second in points with no results worse than seventh; the team's sister entry, which runs in the NAEC, has Jordan Taylor as part of its lineup with Autohaus withdrawing this weekend.

Patrick Long is probably the highest-profile driver to come to the GT ranks this race for Magnus Racing, and co-drives with its usual duo of John Potter and Andy Lally. Fellow Porsche squad TRG is slated to have three cars, including guest drivers Bryan Sellers and Wolf Henzler split among its regulars. Sellers shares the team's No. 66 with Ben Keating and Damien Faulkner; Henzler is listed with Spencer Pumpelly and Al Carter in the full-season No. 67. Carter deputizes for Steve Bertheau, resting after last week's hard crash at Road America.

Mazda and BMW are represented strongly; Mazda by its usual fleet of five RX-8s (two Dempsey, two Sahlen's and the SpeedSource car) and Mid-Ohio winners Turner Motorsport with its M3.

Two other Ferraris make appearances – Extreme Speed Motorsports in its fourth start of the year with Johannes van Overbeek, Guy Cosmo and Mike Hedlund, and AF Waltrip with Rui Aguas and Rob Kauffman.

Another Porsche makes its first Rolex start of the year – Snow Racing/Wright Motorsports with the mother/son combo of Melanie and Madison Snow. The under-the-radar Horton Autosport Porsche squad adds Ryan Eversley in a guest appearance, a reserve for usuals Eric Foss and Patrick Lindsey. APR Motorsport also should be one to watch as it adds a second Audi R8 for Marc Basseng and Frank Stippler this race.

The second-largest field of the season includes 11 DP and 22 GT entrants set to take the green at the Glen.

The Grand-Am Rolex Series Sahlen's Six Hours at the Glen airs live at 11 a.m. Eastern, Sunday on SPEED.