Scott Dixon took another major step towards his second IndyCar Series title by taking a record-equalling sixth win of the season at the Kentucky Speedway, but had to hunt down main rival Helio Castroneves on the final lap to come out on top.

The Kiwi, who had started from pole, appeared to be the man to beat all evening, but was a long way behind Castroneves with four laps to run as the race turned into a battle of wits over fuel. With relatively few yellows to interrupt the flow, the Penske team took the decision to top off Helio's load during the third and final caution, giving him the potential to run to the flag while the majority had to make a splash 'n' dash in the closing moments.

Despite an early challenge from team-mate Dan Wheldon at the green flag, Dixon held the upper hand through to lap 45, when he was passed by the rapid Vitor Meira, the Brazilian having dogged the Ganassi car's tyre tracks for the opening quarter of the race. Meira's lead was short-lived, however, for the Panther Racing team again proved less than a match for Ganassi in the pits, with Dixon regaining the point after managing to stretch his fuel a further lap.

Wheldon also beat Meira off pit-road, the pair having stopped together on lap 51, but had nothing for his team-mate after a brief look at top spot in traffic on lap 59.

At this point, neither Castroneves or fellow Brazilian Tony Kanaan had shown anything like front-running potential, occupying spots outside the top ten as they struggled to get their cars handling as they wanted. Both, however, made adjustments at the first opportunity, and gradually came back into contention.

Instead, the chasing pack was headed by AGR duo Marco Andretti and Hideki Mutoh, with Ed Carpenter and Ryan Briscoe also looking racy through the first half of the race.

Dixon continued to lead when the second caution of the race was called for debris following a clash between duelling dames Sarah Fisher and Danica Patrick. Fisher appeared to be at fault, coming down on her rival prematurely heading into turn three, but neither car was terminally damaged.

The ensuing yellow, however, allowed the majority of the field to pit for fuel and tyres, with Dixon again heading the race off pit-lane while Hunter-Reay spun while avoiding a potential clash with Buddy Rice. At the restart, Wheldon quickly dropped behind Andretti, as the #26 began a charge that would keep him in contention until the closing stages.

Like Meira before him, however, Marco was easily able to stay with the leader, but found it hard to make the pass that would give him the advantage, bobbing in Dixon's wake until lap 121, when the Kiwi's spotter failed to notify him about the off the pace Enrique Bernoldi emerging from the pits. Dixon found himself having to lift to avoid the Brazilian, allowing Andretti, who was on a higher line, to slingshot into the lead, and Wheldon, who was keeping tabs on the lead battle, to assume second place.

Again, however, the new leader found his position at the front of the field short-lived, with the caution flags flying for a third time just twelve laps later. Once more, one of the race's three female participants was involved, this time as Milka Duno smote the turn two wall in her Dreyer & Reinbold entry.

As expected, the majority of the field reported for fuel and tyres but, with the clean-up extending the yellow, the canny ones returned for a top-up shortly before the restart. Mutoh and Castroneves appeared to be the best-placed of those making the strategic move, although the AGR rookie was to be sidelined by mechanical problems not long after.

Castroneves, meanwhile, dropped to the tail of the top ten following his brief stop, just maintaining a place on the lead lap as Dixon again led the pack through the green.

The points leader wasn't having it easy, though, with team-mates Andretti and the resurgent Kanaan both taking a look at the #9 before the latter dropped away and allowed Andretti and Meira to take up the attack.

This time, the pressure took less time to work, as Andretti swept around the outside of turn two to reclaim the lead, and Meira took advantage of the looking Ernesto Viso to slot into second. The Venezuelan, who has made something of a reputation for himself this season, had not hampered Dixon, but the Kiwi seemed to take a 'championship decision' not to challenge Meira in what could have been a three-abreast situation, preferring instead to head for a decent points haul with his main rival several places further back.

Unbeknownst to Dixon, however, Castroneves - chasing his first win in 29 races dating back to St Pete 2007 - was playing a different game, and really came to the fore when the yellow that the leaders had been hoping for failed to materialise in the closing stages.

Although Dixon managed to run fully five laps longer than either Andretti or Meira, he still emerged behind the Penske driver, with little over six laps in which to close a near full-lap gap.

Helio was having to run lean, being passed by several drivers a lap down on the leaders, and Dixon, Andretti and Meira quickly ate into his advantage, entering the final lap within spitting distance of the Brazilian.

Through turns one to three, Castroneves held the upper hand, still with a gap back to Dixon, but four proved to be a turn too far, and the Ganassi machine swept by with time to spare before the chequer. The margin of victory proved to be little over half a second, with Andretti and Meira just unable to overhaul Helio before the line.

Dixon's victory was his sixth of the year, equalling current Ganassi team-mate Wheldon's record haul from the 2005 campaign, and extended his advantage over Castroneves in the title battle. The Kiwi also easily took the three bonus points for leading the most laps, and now heads his rival by 73 points with three races to run.

Wheldon, fifth on the day with his job at Ganassi in question following the team's recent, unsuccessful, pursuit of Kanaan, and the Brazilian, who managed only eighth in the week he re-signed with AGR for five years, remain outsiders in the title fight, but both Briscoe, who beat Kanaan to the flag by one spot, and Patrick, who led a lap after starting on the final row but came home a lapped eleventh, are now out of the equation.

Carpenter claimed sixth place after another strong showing for the Vision team, while Hunter-Reay - who did not lose a lap during his pit-lane faux pas - and Rice rounded out the top ten.

Patrick came out on top of the female battle despite her lowly qualifying position, but benefited from Fisher's late pit-stop to overcome a spirited performance from the self-run entry as the Dollar General car came close to achieving its pilot's aim of a top ten result before having to settle for 15th.

Mutoh's retirement saw him join Darren Manning - the Briton robbed of another top ten finish - AJ Foyt IV, Duno, Bernoldi, Marty Roth, NHLR twins Justin Wilson and Graham Rahal, and the luckless Will Power on the sidelines, the Australian having brought out the opening yellow on lap two when a suspension failure saw him brush the wall and head for a lap five-retirement.

The series now takes another week's break before heading into the three-race back-to-back stretch that will decide the outcome of the championship, starting with the road course at Infineon Raceway on 24 August, although Dixon's current run could see him claim the title well before the final chequer at Chicagoland early next month.