Leinster came storming back to maintain their 100 per cent European Champions Cup record with a 22-17 win over Exeter Chiefs and Anthony Watson's double gave Bath victory over Toulon in a classic at The Rec.
Exeter travelled to the Aviva Stadium smarting from a home defeat to Leinster last weekend and looked set to gain revenge when they led 17-3 late in the first half, Sam Skinner and Luke Cowan-Dickie scoring tries.
Leinster lost Jonathan Sexton to a head injury, while Cian Healy was fortunate to escape with just a yellow card for a forearm on Cowan-Dickie at a ruck. Scott Fardy was also sin-binned as the Premiership champions had much the better of the first half.
Leo Cullen's Pool 3 leaders hung in there and Isa Nacewa's fifth penalty reduced the deficit to only two points, before Luke McGrath took a pass from Dan Leavy, which looked suspiciously close to being forward, to dart away for a decisive try 10 minutes from time.
Leinster are five points clear of Montpellier, who moved above Exeter courtesy of a 36-26 victory against Glasgow Warriors at Altrad Stadium.
Glasgow led 19-14 at the break, but Henry Immelmann claimed a second-half brace as Montpellier came out on top in a pulsating clash to keep themselves firmly in the hunt for a place in the last eight and leave the Warriors still without a win.
Toulon left it late to beat Bath last Saturday but Todd Blackadder's men gained revenge seven days later, going top of Pool 5 with a thrilling 26-21 success.
Beno Obano crossed in the first minute, while Watson dotted down twice, the second a brilliant solo effort, before the Premiership side soaked up huge pressure in the closing stages to edge it.
Scarlets were forced to charter a flight for a clash with Benetton Treviso due to an air-traffic control strike in Italy and back-to-back triumphs have seen their Champions Cup campaign take off, Gareth Davies scoring two tries in a 31-12 win for the Welsh side which leaves them only a point behind Bath and Toulon.
Racing 92 are second in Pool 4 following a 29-7 bonus-point win over Top 14 rivals Castres, although Juan Imhoff took the gloss off the result when he was shown a red card for a headbutt.