Barros flawless for Estoril pole.

Having led every one of the three free practice sessions that preceded today's qualifying session for the Portuguese Grand Prix, Camel Honda rider Alex Barros then completed a perfect sweep by taking a tense pole position at Estoril this afternoon.

Barros had finished Saturday morning's third and final session just 0.007secs ahead of Sete Gibernau - who had a lucky escape after a heavy tumble from his Movistar Honda - while factory Honda rider Max Biaggi and Yamaha's world champion Valentino Rossi completed a top four separated by just 0.13secs.

Into this afternoon's one hour qualifying session and the action was instant; Biaggi ran into the gravel in the opening seven-minutes, then 2004 event pole sitter Makoto Tamada fell at the same left hand turn that had seen Gibernau and Troy Bayliss highside (Tamada would later be seen with an ice pack on his right wrist), while two-minutes later Ruben Xaus added another minor 'off' to his ever increasingly crash list.

Meanwhile, the RCV trio of Gibernau, Biaggi and Barros were slowly lowering the top lap time and Barros's best practice lap of the weekend, a 1min 38.516secs circulation set on Friday afternoon, would be beaten by Gibernau within the first 20-minutes. By that stage Biaggi was 0.18secs behind the Catalan with Barros a further 0.2secs adrift in third.

Gibernau's 1min 38.363secs would lead the field through to the appearance of qualifying tyres at the 45-minute mark, after which Ducati's Carlos Checa was the first to strike - the Spaniard seizing a huge 0.715secs advantage over Gibernau thanks to the super sticky Japanese tyres, with the second Marlboro Ducati of Capirossi sitting third and Edwards fourth.

Gibernau would trim Checa's lead to 0.506secs soon after - and his time was then exactly matched by title rival Rossi, who had jumped up from fifth - before the majority of the field stopped for their final tyre change.

When they emerged the closing stages of the session saw Melandri grab a stunning second position (+0.252secs) on his spare bike after an earlier accident, before Movistar team-mate Gibernau returned to the top... only for Barros to snatch it from him, by 0.174secs, mere seconds later.

The last minutes saw Gibernau make a determined attempt to regain pole, but was left 0.127secs short, while Rossi put his M1 on the outside of the provisional front row after lapping 0.4secs from Barros.

However, the charging Checa was also on a quick lap - and fastest of all at three-quarter lap distance; he would ultimately lose out in the final sector, but still snatched third from Rossi to put the Italian onto row two of tomorrow's race.

The Gauloises Yamaha star will be joined by countryman Melandri, who claimed fifth after a strong comeback, while Capirossi completed the qualifying top six despite his injured ankle.

Edwards and Biaggi continued to match each other's progress, although neither was as far up the order as either they or their new factory teams would expect; the pair claiming seventh and eight respectively for tomorrow's race. At least it was an improvement on their 15th and 16th grid positions at Jerez.

Behind them, Biaggi's Repsol Honda team-mate Nicky Hayden rounded out row three after losing the front and falling from his number one bike at the 38-minute mark, while the sole Kawasaki of Shinya Nakano claimed tenth. John Hopkins again claimed top Suzuki honours despite also falling while on a quick lap in the last 15-minutes.

Meanwhile, Tamada sat out much of the session after his earlier fall, leaving the Konica Minolta Honda rider last on the grid and in doubt for the race after an obvious injury to his wrist.

Full times to follow...

Qualifying:

1. Barros
2. Gibernau
3. Checa
4. Rossi
5. Melandri
6. Capirossi
7. Edwards
8. Biaggi
9. Hayden
10. Nakano
11. Hopkins
12. Xaus
13. Bayliss
14. Roberts
15. Elias
16. Rolfo
17. Ellison
18. Byrne
19. Battaini
20. Tamada