Tries from centre Virimi Vakatawa, wing Teddy Thomas, fly-half Finn Russell and flanker Wenceslas Lauret ensured a maximum five-point haul and lifted the TOP 14 club to the head of Pool 4 on points difference from Munster Rugby.

The Irish province had launched their bid for a third European Cup by storming home 32-13 at PRO 14 rivals Ospreys, who conceded tries from prop Jeremy Loughman, wing duo Keith Earls and Andrew Conway, and prop James Cronin, with Cronin grabbing the bonus-point score in added time.

Pool 5 also has joint leaders after Round 1 in Toulouse and Connacht Rugby, with four-time winners Toulouse having opened with a thrilling 25-20 triumph at Gloucester Rugby after trailing 20-9 at half-time. Full-back Thomas Ramos was their hero with 14 points.

Connacht then joined the French club on four points thanks to an even closer victory - 23-20 at home to Montpellier, who were sunk by a 67th-minute Conor Fitzgerald penalty.

Four-time winners Leinster Rugby and 1999 champions Ulster Rugby completed an outstanding weekend for the Irish provinces with contrasting wins, Leinster cruising to a 33-19 home success against Benetton Rugby and Ulster squeezing home 17-16 at Bath Rugby.

A hat-trick of tries from centre Garry Ringrose helped Leinster to the bonus-point victory that lifted them to the top of Pool 1, while Ulster were grateful to 12 points from scrum-half John Cooney and a last-gasp interception from wing Jacob Stockdale for second place in Pool 3.

Ahead of Ulster are 2019 Challenge Cup winners ASM Clermont Auvergne, who marked their return to Europe’s elite with an exhilarating 53-21 home drubbing of Harlequins. Fijian duo Peceli Yato and Alivereti Raka both notched doubles in a seven-try bonanza.

It was a different story for 2019 Challenge Cup runners-up La Rochelle, though. They slumped 31-12 at home to Exeter Chiefs, who marched to the top of Pool 2 via tries from lock Dave Dennis, wing Tom O’Flaherty, centre Henry Slade and No.8 Sam Simmonds.

Elsewhere, Northampton Saints made an excellent start on their return to the Champions Cup with a 25-14 home triumph over TOP 14 leaders Lyon in Pool 1 thanks to 20 points from fly-half Dan Biggar and Glasgow Warriors battled to a 13-7 home win against Sale Sharks in Pool 2.

Racing 92 - twice runners-up in the European Cup in the past four seasons - underlined what a threat they are going to be in this season’s Heineken Champions Cup by beating defending champions Saracens 30-10 in Paris in Round 1.