Capirossi edges out Rossi for provisional pole.

Loris Capirossi emerged on top in Assen first qualifying after a thrilling duel with countryman Valentino Rossi, that pushed the pair of Italians over 0.6secs clear of the rest of the field.

Free practice had seen Rossi once again leading the way - by over 0.5secs - from his best friend Max Biaggi, with Carlos Checa third fastest ahead of the West Honda Pons duo of Alex Barros and Loris Capirossi.

Early leaders in the one hour session were Checa, followed by Kenny Roberts and in turn Biaggi, before Checa once again went to the top as the 500cc stars found their feet around the daunting Dutch track.

Ten minutes gone and Suzuki rider Roberts was once again on top, from Repsol Honda's Tohru Ukawa, with Biaggi putting the red Marlboro Yamaha into third ahead of last year's winner Alex Barros.

By this stage Rossi was in fifth, 1.159secs behind Roberts, and putting in ever quicker laps, until with 47mins to go "The Doctor" had moved into third, and cut the deficit to 0.596secs.

Meanwhile, local hero Jurgen van den Goorbergh had put his Proton KR three-cylinder machine into tenth, with a quarter of the session gone, before returning to the pits for modifications.

A brief lull followed before the majority of the riders returned to the track with a third of the session gone. Main improver was Barros, the Brazilian moving into second behind Roberts as he trimmed a few hundredths off Rossi best, but he was still over 0.5secs away from the American.

As the half-hour mark approached, Capirossi, who had been down in fourteenth, found almost 2 seconds (on his ninth lap) to leap straight into provisional pole position on his black and white Honda NSR 500.

Soon after, Tohru Ukawa crashed out of the session after dropping his Honda in the first part of the lap, the 500cc rookie shaken - but fortunately unharmed. By contrast, fellow rookie Shinya Nakano put his Gauloises Tech 3 Yamaha into third, making him easily the fastest Yamaha at that stage in the session, with Checa the next quickest in seventh.

23mins top go and Rossi took to track - and was soon throwing his Nastro Azzuro Honda viciously over the kerbs - but it worked, and the young Italian took the provisional pole, by just 0.004secs ahead of Capirossi, while Norick Abe shot to fourth on his d'Antin run Yamaha.

Also on the move was Alex Criville, Repsol Honda rider putting memories of past injuries sustained at Assen firmly to the back of his mind, as he rode smoothly to sixth, before improving on his next lap - but not by enough to move him any further up the grid.

Into the final quarter of the session and Kenny Roberts was back on track to try and retake the pole. But the Americans first lap was a few tenths adrift of Rossi - and no personal improvement - and by now the main threat was again coming from Loris Capirossi, who was flying around the 6.9km circuit, and went a massive 0.603secs faster than anyone to take pole with just over 10mins to go.

At around the same time Shinya Nakano threw his blue machine into the gravel trap, the usually mistake free Japanese rider cart wheeling after his machine, before returning to the pits to jump on the spare bike.

Nakano's teammate Olivier Jacque, finally returning to form after his injury stricken year, moved into eleventh - ahead of Haga - as the Frenchman's return to fitness continues.

5mins to go and Barros was threatening his teammates time - eventually stealing second from Rossi, but the Italian himself was over 0.5sec faster as he approached the final section of the track, and although the bright yellow machine was slower through the final sector, he still took pole by 0.221secs.

Capirossi responded with just a few minutes to go, the man in black rising to the challenge of his countryman to take the provisional pole back by 0.232secs, as both riders seemed to find more and more speed whenever they took to the track.

With just seconds remaining Barros crossed the line to start his final lap, and move up from his current third position. His first sector was a personal best - but not a threat to the top two, however Barros caught Ukawa (who was on a slow lap) towards the end of the lap and was blocked by the Japanese rider. The pair 'battled' their way through the final chicane - with Barros banging the fuel tank in disgust as he abandoned the lap and cruised over the line.

Full results to follow...

1. Capirossi
2. Rossi +0.232secs
3. Barros +0.921secs
4. Roberts +0.932secs
5. Abe +1.290secs
6. Biaggi +1.389secs
7. Criville +1.504secs
8. Ukawa +1.733secs