Australian star Kurtley Beale was in the thick of things on his debut for Wasps as he scored a try after just seven minutes before being sin-binned for a high tackle on Niyi Adeolokun which brought a caution at the Ricoh Arena.
Beale was coming off some six months on the sidelines nursing a knee injury suffered while still with Super Rugby outfit Waratahs.
Sweeping up a maximum five points in sealing a bonus point, Wasps stung their rivals as No8 Nathan Hughes, skipper Joe Launchbury -- returning from a ban -- and wing Josh Bassett also went over while fly-half Jimmy Gopperth added two penalties and three conversions.
Scrum-half Kieran Marmion and replacement Rory Parata scored tries for the Irish while fly-half Jack Carty converted both and added a penalty.
The two sides will meet next week in Ireland with Wasps defending a three-point lead over Connacht while they currently stand four ahead of French giants Toulouse.
South African coach Jake White saluted his Montpellier side after they swatted fellow French side Castres 32-14, nabbing four tries to sweep home despite an early sending off for Georgian tighthead prop Davit Kubriashvili.
"To win with 14 guys in scoring four tries is good for the group. After the sending off I thought the match was finished, so that's why the group turned in an exceptional performance. The forwards were fantastic," said White.
"It's a big success to pull out such a match against a very powerful Castres side," White added after the southerners bolstered their chances of emerging from Pool 4.
Montpellier centre Alexandre Dumoulin said: "We told ourselves it was going to be very tough after the sending off. We dug deep to find the necessary ingredients to pull out the win. We thought it would be asking a lot to get the bonus point on the board with 15 never mind 14.
"The win has done us the power of good and we're still in this competition."
Leinster had put the pressure on, the Irish winning at Northampton 37-10 on Friday and they lead Montpellier by a point owing to a defensive bonus point garnered in their earlier 22-16 loss to the French at the Altrad Stadium.
Later action Sunday pitted Welsh outfit Scarlets against Toulon in the south of France in Pool 3, where reigning champions Saracens did their chances of advancing no harm at all with Saturday's 50-3 crushing of fellow English side and tailenders Sale.
Saracens have won all three of their encounters to date after edging Toulon 31-23 and beating Llanelli.
Rounding off Sunday's action was a Pool 5 meeting between Exeter and Bordeaux, who were looking to overhaul an Ulster side which Saturday handed French hopefuls Clermont their first defeat in an exciting 39-32 finish.
Clermont shrugged off a measure of their disappointment in landing two bonus points.
The five pool winners will qualify for the quarter-finals along with the three best-placed runners-up.