Watch: Former All Black centre lays out French flyhalf Matthieu Jalibert

Former All Blacks and Blues midfielder Francis Saili has opened the Top 14 season in bruising style, delivering a crunching cover tackle on French flyhalf Matthieu Jalibert in Biarritz Olympique's upset win over the Bordeaux Begles.

Previously in the Pro D2 league, Biarritz earned promotion to this year's Top 14 season after beating Bayonne in the promotion-relegation clash. Heavyweights Bordeaux finished fourth in the Top 14 last season so Biarritz headed into the opening game as severe underdogs.

Bolstered by the likes of former All Black Francis Saili, who was signed from Harlequins, and former Wallabies Tevita Kuridrani and Henry Speight, Biarritz came out and stunned Bordeaux in the first half racing out to a 17-3 lead.

With three minutes remaining in the half, Bordeaux flyhalf Jalibert sparked a break down the right touchline only to be bundled out of play by a flying Saili in cover defence who put a dominant tackle on the young French 10.

A shaken Jalibert threw his arms up in the air in protest to the touch judge to no avail, as the home crowd cheered on their newly promoted side.

The tackle by Saili was his second big defensive play of the game, after an earlier rush tackle helped set up Brett Herron for the first try of the game.

Saili flew out of the line to put a hit on an unsuspecting Bordeaux reciever, who spilled the ball into the arms of Herron who raced away downfield to score against the run of play.

The Biarritz crowed was sent into raptures as their side took a 10-0 lead following the try.

The home side added another try and a penalty goal early in the second half to extend the lead to 27-3 which proved too much of an ask for Bordeaux to come back from, handing the club a massive first scalp in the Top 14.

In other Top 14 fixtures, Ngani Laumape made his debut for Stade Francias in a 36-21 loss to powerhouse Racing 92 on the back of a solid performance from former Wallaby Kurtley Beale who ran for 109 metres and had two line breaks.

Laumape was held to 15 run metres on seven carries in his Top 14 debut, but was able to shake four defenders and provide a couple of offloads. Wallabies wing Sefa Naivalu bagged a try for Stade on the right wing.

Montpellier and Toulon shared a 24-all draw at the Stade Mayol after an extra time try to former England international Zach Mercer. Montpellier stole a win from Toulon's grasp after eight penalty goals from Anthony Belleau.

With time up on the clock, Montpellier received a penalty from directly in front which Springbok centre Jan Serfontein tapped quickly. After multiple pick-and-go attempts, Mercer picked up the ball with the line begging and scored right next to the posts to rob Toulon of the match.