The Scottish international, who will be looking to add to his six tries in eight Challenge Cup games when Worcester get their campaign under way at Newcastle Falcons on December 10, went over on 10 minutes before crossing again in the second half.

Jamie Shillcock had touched down before Van der Merwe’s first score and rounded off an impressive Warriors performance with his second try on 68 minutes.

There was no such success for EPCR Challenge Cup team London Irish against Heineken Champions Cup opposition, as they lost 45-33 at home to Bristol Bears.

Irish went over five times, through James Stokes, Mike Willemse, Matt Rogerson, Terrence Hepetema and Kyle Rowe, but were outgunned by the 2020 Challenge Cup winners.

In the TOP 14, RC Toulon came out on top in a battle of EPCR Challenge Cup sides, winning 13-9 at home to Biarritz Olympique.

Facundo Isa notched the only try of the game for three-time Challenge Cup finalists Toulon, with all Biarritz’s points coming from the boot of Ilian Perraux.

Meanwhile, an Afusipa Taumoepeau hat-trick saw USAP win 22-13 at home to last season’s Heineken Champions Cup finalists, Stade Rochelais and Zack Henry kicked all Section Paloise’s points at home to Stade Français Paris, with the EPCR Challenge Cup team triumphing 18-9.

However, it wasn’t to be for CA Brive, who were edged out 23-22 at Castres Olympique, despite Pierre Tournebize’s try and Tedo Abzhandadze’s 17 points with the boot.

Elsewhere, Jean-Marc Doussain grabbed a consolation try as Lyon were beaten 30-8 at last season’s Challenge Cup winners, Montpellier Hérault Rugby.

British and Irish Lions wing Duhan Van der Merwe scored two tries as EPCR Challenge Cup side Worcester Warriors won 27-14 at home to Heineken Champions Cup outfit Sale Sharks in the Gallagher Premiership on Saturday.