Just nine points split Michael Caine and Tim Harvey at the head of the title race as the Porsche Carrera Cup GB heads to Scotland for rounds 15 and 16 at Knockhill (16/17 August).Caine (Team Parker Racing) edged ahead and Harvey (Red Line Racing) with a fantastic double victory last time out at Oulton Park, but Knockhill is famed for delivering exciting and unpredictable races. While Harvey won both races at Snetterton a month ago, Caine came back strongly with a fine weekend at Oulton Park and there is likely to be very little between them in Scotland.With every one of the 20 round counting towards the final positions, both drivers know that they must keep on finishing strongly. To date, Caine has finished every round, while Harvey has recorded just one non-finish at Thruxton in May.A year ago, Steven Kane arrived at Knockhill with a significant lead in the championship, but left the track with his title hopes severely dented. Caine and Harvey both have bags of experience of the challenging moorland track and know that the tight confines of Knockhill and its notoriously changeable weather could make this a pivotal weekend in the title race.Leading the chase of Caine and Harvey is Tim Bridgman (Team Parker Racing), and with six races still to run his title challenge is far from over. Battling to catch Bridgman, meanwhile are Jota Sport's Sam Hancock and Phil Quaife, while Charles Bateman (Team Parker Racing) will be bidding for another podium finish. Hancock scored his first Carrera Cup victory at Knockhill a year ago, and will be working hard to repeat that result this time around. Adding further quality to the pro entry will be Pippa Mann (Team Eurotech), who rejoins the championship for her second weekend in a Porsche.In the pro-am1 category, the battle continues between Tony Gilham (ReDesign Racing) and Nigel Rice (Red Line Racing), and the gap in the pro-am1 points is now down to 10 as Rice continues to chase his rival. The additional point for fastest lap in the category in each race could yet prove critical as the title contest heads into the closing six races.Meanwhile teenage sensation Glynn Geddie (Parr Motorsport) is setting the pace in the pro-am2 category and is sure to fly on his home track. Glynn has done more racing laps at Knockhill than at any other venue and he should be right up among the leading times. Bob Lyons and Tommy Dreelan (Apex/Qserv) pack out the home contingent in the category, while Graeme Mundy (RSS Performance) is another leading pro-am2 contender and will be battling to catch Dreelan at the head of the pro-am2 points.Finally, Autosport journalist Ben Anderson and young Scot Rory Butcher will race the PCGB entries.After qualifying on Saturday morning, round 15 will be at 9.40am on Sunday morning, with round 16 scheduled for 2.30pm on Sunday.