Northampton Saints completed back-to-back victories over English rivals Bristol to book their place in the quarter-finals of the European Challenge Cup.
Scrum-half Ben Fodden sealed a bonus-point win with the first and last of the Saints' four tries either side of scores from Jon Clarke and Chris Mayor.
But they were forced to survive a late scare as Bristol rallied from 25-9 behind to snatch a losing bonus point through tries from Lee Robinson and Luke Arscott that set up a thrilling climax to the all-English derby in Pool Two.
Victory at the Memorial Ground ensures Northampton will top the pool, with two rounds still to play, having taken a maximum 20 points from their first four games.
Saracens have one foot in the last eight after beating Bayonne 36-0 in a fiery game at Welford Road that saw five yellow cards.
Gordon Ross kicked Saracens into a 12-0 lead before Neil de Kock sent Kameli Ratuvou over for the opening try on 30 minutes.
However the half ended with Nicolas Laffite, Census Johnston and Julian Fiorini all the sin bin in a bad-tempered Anglo-French clash.
De Kock, Noah Cato and Chris Jack all scored in the second half to clinch a bonus point before Hugh Vyvyan and Anthony Etchegaray were binned for fighting.
Newcastle Falcons struggled for the second week in a row to shake off Overmach Parma before holding out for a 21-16 win at Kingston Park.
Jamie Noon looked to have put the Falcons on course at the start of the second half with the Falcons' third try, following scores from Rob Miller and Micky Young.
But Parma replacement Juan martin Soffredini crashed over on 58 minutes to salvage a losing bonus point for the Italians that leaves Pool Four in the balance.
Newcastle are now two points behind leaders Brive who eased to a comfortable victory at Cetransa El Salvador. Former England wing Ben Cohen clinched a bonus point with the fourth of Brive's nine tries in a 55-5 win in Spain.
As part of the build-up to next month's Cardiff 2014 Heineken Cup and Amlin Challenge Cup finals weekend, ERC has joined forces with the WRU, Cardiff Blues and adidas to develop an annual grassroots community rugby programme targeting young players.
The Ulster Rugby full back, Jared Payne (No 15), has been suspended for two (2) weeks following an independent Disciplinary Hearing in Dublin arising from the Heineken Cup quarter-final match against Saracens at Ravenhill Stadium on Saturday, 5 April.