Paris - Saracens continued their perfect start to the season with a thumping 45-10 defeat of French minnows Oyonnax on Sunday.
The English champions maintained their stranglehold of Pool A with a bonus-point victory after scoring six tries that left them nine points clear of Ulster, who thrashed record four-time champions Toulouse 38-0 on Friday night and have a game in hand.
It was a ninth straight win in all competitions for Sarries who also lead the English Premiership after a perfect six from six start in domestic competition.
On paper, Sarries looked too strong for the Top 14 basement sitters, and that proved the case in a dominant first half in which the Oyonnax scrum was crushed time and again.
England flyhalf Owen Farrell had given the visitors an early lead from the boot before referee Marius Mitrea awarded a penalty try on 18 minutes after Oyonnax collapsed at the scrum.
Farrell was then the architect of a second try when his break and long pass to Chris Wyles allowed the American wing to pop the ball inside for full-back Alex Goode to scamper over down the left.
Moments later, Wyles popped up on flanker Will Fraser's shoulder after another break from Farrell to go over under the posts.
Farrell kicked all three conversions as Saracens turned around leading 24-3 at the break.
The bonus point came in the 49th minute as Saracens worked an overlap on the left and flanker Michael Rhodes drew in the defence before passing inside for lock Maro Itoje to go over.
A minute later, South African Rhodes almost went the whole way himself but after being caught 10 yards shy of the line, he found scrumhalf Richard Wigglesworth to add try number five.
There was still half an hour to go but the game was dead and Saracens lifted their foot off the pedal.
It allowed Oyonnax replacement scrumhalf Arthur Aziza to claim a well-deserved try late on for the persistent hosts, although Sarries still had the last word when South African Schalk Brits burrowed over.
On Saturday, New Zealand legend Dan Carter made his Racing 92 debut as the French side brushed aside Northampton 33-3 in Pool 3.
French champions Stade Francais got their first win of the competition this season with a seven-try 50-17 romp away to Italian whipping boys Treviso.
Leicester are still in control of that Pool 4, though, after an impressive 31-19 victory at Munster maintained their perfect start in the competition.
Exeter produced the performance of the day, though, in beating last season's finalists Clermont 31-14 in Pool 2.
Later on Sunday, reigning champions Toulon host fellow three-time winners Leinster.