A race two mistake by Josh Coppins threw the Grand Prix of Germany wide open, eventually allowing MX1 rookie David Philippaerts to take his first premier-class victory.
After a dull opening race around the revised Teutchental circuit, in which championship leader Coppins won comfortably from Yamaha Rinaldi team-mate Marc de Reuver, the New Zealander looked set to complete a perfect double when he worked his way swiftly past early leader Mike Brown in race two.
But pole sitter Coppins then made a rare mistake while safely out front, handing the lead - and potentially grand prix victory - to de Reuver. The popular Dutchman looked on course for his first MX1 triumph as he kept his advantage over a frantic fight for second, led by fellow rookie Philippaerts - but Marc too made a mistake, tripping over his 450 in a deep rut at the bottom of a hill.
That put Philippaerts at the front of a thrilling six-rider battle that also consisted of Steve Ramon, Sebastien Pourcel, Kevin Strijbos, Coppins and Gordon Crockard. Pourcel, another class rookie, pushed past Ramon and hounded Philippaerts during the final laps - by which time rain had well and truly arrived - but the Italian held firm and punched the air with delight as he claimed his and KTM's first victory of the season.
"Today I pushed hard and it was a good result for me," smiled David, fifth in race one. "Now I will just try to be relaxed and do my best and take it race by race."
Team boss Stefan Everts was also delighted: "Even though David struggled a bit in the first heat, his speeds were up with the best. He was stuck with a group of seven and that is never easy. But then in the second he fought very hard all the way. He was very good and very concentrated through the entire race, focusing on the action in front of him and that was exactly the right thing to do," declared the former ten time world champion.
A pair of third places for Suzuki star Ramon cost him overall victory by just one point, while Coppins - equal on points with Ramon - collected the final podium position despite losing fifth to a charging Crockard in the closing stages of race two.
Coppins thus leaves round five with a 43 point advantage over Strijbos - the only rider other Philippaerts to defeat Coppins this season, but just sixth and fourth on Sunday.
In the MX2 class, Antonio Cairoli continued his unbeaten run with a perfect five victories from five GPs. The Italian held off reigning champion Christophe Pourcel for victory in both races, while Tyla Rattray completed the podium after 4-3 finishes.
In the Womens' World Cup competition, Honda's Larissa Papenmeier turned pole into a home victory, in front of Kawasaki Elf Team Pfeil's Maria Franke and GPKR's Livia Lancelot.
KTM Germany's Stephanie Laier won race two, but a mechanical failure in the first heat left her down the order overall while defending champion Katherine Prumm finished fourth overall, despite falling in both races.