World champion and championship leader Italian Valentino Rossi has never won a premier class event at Assen, the only event remaining from the original 1949 season. Rossi has won both 125 and 250cc races in Holland but finished second last year behind the Yamaha of Max Biaggi in the race, which was shortened because of rain. This year Rossi has dominated the MotoGP World Championship with five wins out of six riding the RC211V five-cylinder 990cc Honda. He leads impressive team-mate Tohru Ukawa by a massive 48 points in the title chase, with Honda having a clean sweep so far because Ukawa is the only rider to beat Rossi this season.

The Honda duo and their RCV machines form a formidable team that have not been cracked this season. However, there are signs the challenge is about to hot up with Yamaha's YZR M1 four-strokes in the capable hands of Biaggi and Carlos Checa improving each race. The introduction of a new chassis and considerable improvements to the engine and electronics have put Yamaha on the podium in the last three races. Biaggi started the last race in Barcelona from pole and Checa led half the race before finishing third.

Suzuki, who have a great record at Assen with Kevin Schwantz winning three times and holding the lap record at the old slightly longer circuit, arrive full of confidence after a good two day test following the Grand Prix in Barcelona. Their GSV-R four-stroke bike has made tremendous strides since its debut in January. The Suzuki team will field three riders once again with Japanese Superbike champion Akira Ryo joining former world champion Kenny Roberts and Spaniard Sete Gibernau.

Another four-stroke team making massive progress is Aprilia with their RS Cube, which will delight the Assen crowd with its glorious sound. Frenchman Regis Laconi has scored points at every round on the bike and is tenth in the championship.

The two-stroke riders will certainly fancy their chances round Assen with plenty of fast technical bends and not too many slow corners and long straights. The Honda Pons duo of Loris Capirossi and Alex Barros have consistently been quick this season and will hope for some more success in the Netherlands. Barros, who was fifth in Barcelona, won the 500cc race at Assen two years ago. Capirossi, who's third in the championship, eight points in front of Biaggi and Checa, has won two 250cc races in Assen and was third in the 500cc event for the last two years.

Jurgen van den Goorbergh makes his appearance in front of his home crowd and will be looking for a change of fortune on Erv Kanemoto's NSR Honda. It's been tough for the popular Dutchman having to help develop the new Bridgestone tyres while adjusting to the NSR. He was brought down in a first bend crash in Barcelona, which also involved the Yamahas of Norick Abe and Shinya Nakano. The Proton KR team are also hoping Assen will suit their three-cylinder 500cc machine. Their new chassis will not be used until the British Grand Prix but in Jeremy McWilliams they have a rider who has tasted success at Assen, winning the 250cc race last year.

Nineteen-year-old American John Hopkins is having a brilliant debut season on the two-stroke Red Bull Yamaha. He's scored points at every round, finished tenth in Barcelona and actually held pole for a couple of minutes towards the end of the final qualifying session. He's joined in the team once again by German Alex Hofmann who replaces the injured Jean Michel Bayle, who in turn replaced the injured Garry McCoy, who hopes to return in two weeks.

Italian Marco Melandri won the 1998 125cc race in Assen when he was just 15 years old. He returns this year in chasing his third consecutive 250cc victory on the Aprilia. Two crashes in Japan and Spain mean that Melandri trails Spaniard Fonsi Nieto by six points in the title chase. Nieto, also riding an Aprilia, has been on the podium at the last five Grands Prix, including two victories, and it promises to be a tremendous battle on Saturday. Italian Roberto Rolfo hung onto third place in the championship after finishing second on the Fortuna Honda Gresini machine in Barcelona while German Ralf Waldmann makes a welcome return to the action, riding an Aprilia.

Nineteen-year-old Manuel Poggiali increased his chances of retaining his world 125cc crown by winning a tremendous battle with 16-year-old Daniel Pedrosa in Barcelona. Riding the Gilera, Poggiali increased his lead to 11 points over Frenchman Arnaud Vincent, who's had a tough time in the last two races.

Because of the World Cup third place play-off all three Championship races will start one and a half hours later on Saturday. The 125 at 12.45 CET, the 250 14.00 CET and the MotoGP 15.30 CET.