Omani racing driver Ahmad Al Harthy is confident of mounting a strong challenge during round four of the 2013 Avon Tyres British GT Championship at Silverstone Grand Prix Circuit this afternoon, Sunday, 26th May, despite a tough qualifying session at the Northamptonshire track yesterday.Going into the longest race of the season so far, a three-hour spectacular, equal sixth in the points standings, the Oman Air Motorbase raceralong with team-mate Michael Caineis determined to try and battle for a podium result knowing race pace has been the duos major strength so far.With significant ballast in the 31-year-olds Porsche 997 GT3R, which is a result of Caines British GT title-winning success from last year, continuing to prove a hindrance to their speed in qualifying, during Saturdays session the pairing had to be satisfied with 17th on the timesheets.Caine was tasked with the 45-minute qualifying run and he managed a best lap of 2m04.074 seconds (106.20mph), placing him just 1.4 seconds shy of pole position but 17th out of the impressive bumper grid of 38 cars.With 180 minutes of racing ahead of the team-mates today though, which will be split evenly between them into two stints each, Ahmad has every confidence of climbing through the order and mounting a consistently strong challenge.It was another tough session yesterday, its all to do with the weight were carrying, said the Oman Air, Oman Ministry of Sports Affairs, Oman Ministry of Tourism, Nawras, National Bank of Oman and Muscat Eye Laser Centre-supported racer, The ballast does affect us badly in qualifying, we feel confident for the race thoughweve been strong in the races all season.Michael had the duty of qualifying and he got everything he could out of the car, we obviously want to be higher up the grid but were feeling very positive. Its a very long race, its mandatory we have two stints each so Ill start and Michael will take the final run to the flag. As always, were happy with our race pace from practice and I really think we can make a strong challenge.Round four of the Avon Tyres British GT Championship at Silverstone Grand Prix Circuit will get underway at 13.00 this afternoon, Sunday, 26th May, and will be screened live on Motors TVplease check local listings for full details.Provisional 2013 Avon Tyres British GT Championship Standings (after Rd3):=6th Ahmad Al Harthy/Michael Caine & Jason Minshaw, 26pts