Reigning Top 14 champions Clermont Auvergne began the 2017-18 season with a loss courtesy of an impressive second-half performance by Bordeaux-Begles at Stade Chaban-Delmas.
Clermont led by seven points at the interval on Saturday, but were beaten 32-25 as Bordeaux - in their first competitive game under Jacques Brunel - came on strong in the second half.
Both sides scored three tries apiece, with Simon Hickey's five penalties proving decisive for Bordeaux.
Racing 92 came roaring back from 18-3 down to record a 25-21 victory over Castres, Louis Dupichot claiming the match-winning try with just three minutes remaining.
Arthur Retiere scored two tries as La Rochelle, who finished the 2016-17 regular season as table-toppers, won 19-10 at Brive in a match featuring two yellow cards for each side, while Lyon won 25-16 at Stade Francais.
On their return to the top flight, Agen suffered a chastening 48-19 defeat against Montpellier, who had seven different try-scorers.
However, fellow newly promoted club Oyonnax were able to hold Toulouse to a 23-23 draw.
-- TOP 14 Rugby (@top14rugby) August 26, 2017
Toulon, the beaten finalists last term, face Pau on Sunday in the opening round's sole remaining fixture.