Dimitri Yachvili potted three penalties to leave the visitors 10-9 behind at the break, but Biarritz were decidedly brittle as Connacht's younger forwards outworked them.

Although Imanol Harinordoquy came off the bench to score an injury-time try, Yachvili missed the conversion for a losing bonus point.

It was a tremendous result for Eric Elwood's men, with Parks guiding a hard-running back-line and man-of-the-match Mike McCarthy marshalling the young guns up front.

With Gavin Duffy, John Muldoon and Nathan White heading the province's 15-man injury list, Parks skippered Connacht and varied the play superbly early on.

After Yachvili nudged Biarritz ahead, Vainikolo struck for a superbly-taken try that really lifted his team-mates and the vocal home crowd.

David McSharry intercepted a pass from Charles Gimenez near halfway and offloaded brilliantly for the Tongan winger to charge away for a score against the run of play.

Parks converted to put Connacht 7-3 ahead and the westerners missed out on a second try when Ireland lock McCarthy failed to spot Robbie Henshaw looping around him in plenty of space.

A series of penalties failed to budge the scoreline with the wind-backed Yachvili missing two shots at the posts, and Parks drifting a long range attempt wide.

The Biarritz talisman was back on target at the midpoint of the first half, his second successful penalty following a decent bout of territory for last season's Amlin Challenge Cup winners.

But Connacht looked the more dangerous of the two sides off limited ball and Takudzwa Ngwenya had to concede a lineout as Tiernan O'Halloran chased hard.

The hosts pressed in the next phase and Parks took the drop goal option, in front of the posts, to reopen the four-point gap.

Biarritz looked lacklustre in thought and deed, and tigerish tackling from the likes of Willie Faloon, Michael Kearney and Eoin McKeon helped Connacht keep their defensive line intact.

However, an advancing penalty count took its toll. Number 8 McKeon was sin-binned for taking out an airborne Iain Balshaw and Yachvili snapped over a classy penalty to make it a one-point game.

Despite their greater experience and strength up front, Biarritz failed to hammer home their numerical advantage and Parks restarted the scoring in the second period with a penalty.

Connacht countered again moments later, tournament debutant Danie Poolman punching down towards the 22. Parks hung up a cross-field kick which O'Halloran was inches away from collecting.

Biarritz introduced the fit-again Harinordoquy as they tried to reassert themselves, but strong carries from McSharry and Henshaw preceded another Parks three-pointer.

Parks and company kicked cleverly to keep Biarritz pinned back and McCarthy and excellent hooker Jason Harris-Wright provided direction for the hard-working home forwards

They forced a scrum penalty that Parks missed to the right, yet further chances came and in the final 10 minutes the former Scotland out-half landed an inspirational drop goal and a third and final penalty.

Biarritz's game descended into niggly phases, with their questionable attitude and temperament resulting in a couple of scraps between the forwards.

They did lift the tempo late on, powerhouse Harinordoquy piling over after O'Halloran was sin-binned during some desperate Connacht defence.

But deservedly Connacht failed to cough up the losing bonus point and they will head to south west France for next week's return leg with renewed confidence.