With the top three overall drivers covered by just five points, action in the Porsche Carrera Cup GB resumes at Donington Park (16/17 May) for rounds five and six of the 20-race season.Strong grids, close racing in all three categories and even more cars expected at Donington are the hallmarks of a cracking season for the 170mph 911GT3 Cup cars. At Brands when the season opened, Tim Bridgman (Team Parker Racing) was mighty and won both races convincingly. But the story was different at Thruxton as defending champion Tim Harvey (Red Line Racing) and Michael Caine (Motorbase Performance) took a win each as Bridgman struggled with oversteer. Added to the mix at Thruxton was championship returnee and 2007 champion James Sutton, back with Red Line Racing; the team that took him to the '07 title. He claimed a podium in the second race and now makes it at least four drivers vying for race wins.Clearly, if Bridgman can recover his Brands form he will be very tough to beat, but Harvey and Caine are formidable opponents and Sutton will almost certainly be bang on the pace, having jumped into the car at Thruxton with no testing. Then, drivers like Carrera Cup Scholarship winners Tom Bradshaw (Team Parker Racing) and Lewis Hopkins (Red Line Racing) are chasing hard, while the championship debut of Aaron Scott (JMH) puts another strong contender into the mix. Bradshaw in particular is expected to be strong at Donington, having struggled with tyre performance somewhat at Thruxton, while Hopkins has already shown impressive pace.Meanwhile, the pro-am1 category is just as competitive and four drivers have each won one of the four races to date. This is a fantastic race within a race and currently Glynn Geddie (Team Parker Racing) has the points' lead from championship newcomer Robert Lawson (JHR) and Tony Gilham (Red Line Racing). However, back in the pack for Donington after missing the Thruxton races will be Brands winner Michael Leonard (Team Parker Racing), while Ollie Jackson (Motorbase Performance) and Derek Pierce (JHR) are two more strong runners in the excellent pro-am1 field.In the pro-am2 category, Robin Clark (Parr Motorsport) has taken the early advantage, but Karl Leonard (RSS Performance) and George Richardson (Motorbase Performance) should both be back on the grid at Donington to challenge for victory. However, John Gaw (Team Kinfaun) will be a major pro-am2 contender on his Carrera Cup debut.Making his 2009 championship debut, and likely to join Gaw as the absolute pacesetters in pro-am2, is Paul Hogarth (IN2Racing), while Bob Lyons rejoins the championship in pro-am2, racing alongside pro-am1 contender Tommy Dreelan in the Celtic Speed squad. Boosting the pro-am2 entry to give the category its biggest field to date will be series newcomer Glen McMenamin (Parr Motorsport).Meanwhile the VIP car will be raced by single-seater ace Aaron Steele as his reward for being one of the six finalists in the Carrera Cup GB Scholarship. Fresh from the A1GP weekend at Brands Hatch, Steele's progress will be watched with interest as he makes his Carrera Cup debut.After qualifying at 2.40pm on Saturday afternoon, the first Carrera Cup race will start at 9.10am on Sunday, with the second race at 3pm.