Ireland international Justin Bishop scored the winner as London Irish bagged a confidence-boosting 20-18 victory in their Challenge Cup match against Auch in France.
The English visitors turned around a 12-18 deficit at halftime thanks to Bishop's fine effort in the 66th minute and are in great shape in the build-up to next weekend's return match.
Both sides - who had never played each other before - scored two tries in an entertaining first half, with scrum-half Brice Salobert and fullback Frederic Couzier getting on the scoreboard for the home side, and fullback Michael Horak and Canadian backrower Phil Murphy replying for the visitors.
Eight points from the boot of centre Anthony Lagardere gave Auch an 18-12 lead at halftime, which former England centre Mike Catt closing the gap with a penalty goal on the hour mark.
Six minutes later, Bishop was over in the corner and London Irish are in the box seat ahead of next weekend's return leg at the Madjeski.
Meanwhile, English club Worcester celebrated their European debut with a hard-fought 14-point victory over French club Brive at the Sixways ground.
Home props Chris Horsman and Steve Sparks scored vital first-half tries in the first leg of round one of the European Challenge Cup, and although Brive outside-half Sebastien Laloo kept the visitors in touch with three first-half penalty goals, Worcester took a 15-9 lead at the break.
Worcester's Samoan centre Dale Rusmussen extended the margin with a well-taken try in the second half, and skipper Pat Sanderson confirmed the victory with his side's fourth try on the hour mark.
Laloo added two further penalty goals, but Brive coach Eric Alegret will demand tries when his side host Worcester at Parc Municipal des Sports in the second leg next weekend.
In Portugal, Scottish side Borders romped home past AA Coimbra, winning 98-3.
Borders scored 16 tries, including three to Test winger Nikki Walker, with fullback Stuart Moffat converting nine of them. He missed his final two shots at goal, and Coimbra were saved the embarrassment of conceding a century of points.
Elsewhere, French heavyweights Pau were far too good for Italian side GRAN Parma, winning 35-15. The former European Shield winners ran in four tries, including a brace to winger Jean-Charles Cistacq, in a comfortable away victory. Agen racked up a half-century in their 50-27 win at L'Aquila, with centre Sylvain Mirande running in three of the French club's seven tries.
Italian side Viadana gave Spanish side VRAC an 88-3 lesson, with former England winger Tom Beim leading the way with four of his side's 14 tries, while French side Beziers beat Padova 57-24 and Montpellier waltzed to a 51-7 away win at Rovigo.
In the evening fixtures there was drama in Grenoble as Dean Richards' French side scored a last-minute penalty to tie with Leeds 9-9.
The Tykes had lead for most of the second half thanks to penalties from Gordon Ross and Tim Stimpson who kicked his first points for his new club with a monster effort.
But a precious win in France was cruelly denied as Grenoble outside-half Maxime Suarez struck a last-minute equaliser to leave the tie perfectly poised for the second leg next Friday night.
The Yorkshire club was unable to match the result of Saracens who managed a win in France. Robbie Kydd grabbed 16 points as Saracens pulled off a surprise 24-16 win over Bayonne. The centre scored the second of his side's two tries as well as adding two penalties and converting Raphael Ibanez's earlier score. That gives the Londoners a valuable three-point lead to take into the second leg at Vicarage Road next Friday night.
In the evening games Narbonne scored 20 unanswered points before Connacht came to life. The Irish proceeded to score 11 points thanks to two penalties and a try from Mark McHugh, but conceded a late try to go down 25-11. And Leonessa were unable to combat the power of Montferrand. They crashed 65-0 to the French side.
On Sunday Cetransa El Salvador made it a red letter day for Spanish rugby as they sent Rugby Parma crashing to a shock 36-12 European Challenge Cup Round 1 First Leg defeat in front of 1,500 fans at their Pepe Rojo ground in Valladolid.
Rugby Parma, who reached the semi-finals of the European Shield last season, found themselves 26 points adrift at half-time as the Spaniards dominated the game.
Four tries in the opening 40 minutes, including a brace from attacking full back Cesar Sempere, as good as sealed Parma's fate.
Two tries from centre Andrea Orsi in the space of three minutes after the break did hint of a Parma comeback but it proved a false dawn for the stunned Italians who also contested last season's Italian Championship semi-finals.
El Salvador regained their composure and when wing Santiago Toca got their fourth of the game with seven minutes remaining, they were assured of taking a healthy 24-points advantage into the second leg in Parma on Saturday. Meanwhile Sale Sharks won the first European Challenge Cup game to be held in Sicily as Chris Mayor, Chris Rhys Jones and Mark Cueto, twice, scored two tries in their unconconvincing 31-22 victory over Amatori Catania.
The directors of ERC voted unanimously at a Board meeting to postpone all decisions including the release of further instalments of ERC's distributable central revenues to the six shareholder countries until 19 February next when the Board will meet again to reconsider the issue.