Sonny Bill Williams scored on his French premiership debut as Toulon opened their Top 14 rugby championship with a 22-16 win over Clermont.

The New Zealand international, who controversially walked out of the Bulldogs NRL club last month, crossed for one of Toulon's three tries as the ambitious club - back in the top flight for the first time in two years - beat last season's Top 14 runners-up.

Former NSW Waratahs coach Ewen McKenzie also made a memorable introduction to French rugby with Stade Francais taking the early lead on the ladder after a comfortable 31-9 defeat of Dax.

Italian Sergio Parisse scored two tries as the Parisians' lopsided win ensured the best possible start for the former Wallaby.

Montauban also claimed a handsome win over newly promoted Mont-de-Marsan 37-19.

But champions Toulouse opened their title defence with a surprise 16-11 loss at Montpellier.

Toulouse were unable to capitalise on their first half domination with Didier Nourault's Montpellier coming out after the break to take and hold on to the lead.

Brought to you by AAP © 2024 AAP