London - Two tries by fullback Mike Brown secured a stunning win for Harlequins at Toulouse on Sunday, blowing Pool Six wide open ahead of the final two Heineken Cup group matches next month.
The thrilling 31-24 victory lifted the English Premiership leaders to second place in Pool Six, one point behind four-times European champions Toulouse who top the standings with 13.
"It was do or die for us in the competition," Harlequins captain Chris Robshaw told reporters.
"I'm very proud of the guys and it was a great day for us. To come here and take the victory is huge and puts our Heineken Cup hopes right back on track," added Robshaw whose team suffered their first defeat of the season at the hands of Toulouse in London last week.
Toulouse had appeared to be cruising to the knockout stages after three successive wins but with third-placed Gloucester overcoming Connacht 23-19 on Saturday, the race to qualify for the last eight is still wide open.
"Maybe we were a bit self-important, like they were last weekend. We are disappointed but the most important thing is that we still have our fate in our hands," Toulouse coach Guy Noves said.
Scrumhalf Jean-Marc Doussain admitted Harlequins had been the more clinical side.
"We had more opportunities but they were more efficient," he said.
Earlier in the day, two penalties by Ireland flyhalf Ronan O'Gara helped Munster edge out the Scarlets 19-13 and move five points clear at the top of Pool One.
Victory ensured the twice Heineken Cup winners kept their 100 percent record in this year's competition and move to the brink of the knockout stages but their coach Tony McGahan warned his players not to ease off.
"We recognise we still have a lot of work to do and that this Pool isn't anywhere near finished. We know that and we know it is going down to the wire," he said.
Northampton's emphatic 45-0 win over Castres increased the possibility of the last year's Heineken Cup runners-up qualifying for the Challenge Cup by finishing third in Pool One.
Aware that they could not qualify for the knockout stages of European rugby's premier club competition after losing their first three games, Northampton cheered the home fans with five second-half tries against the French side.
Defending champions Leinster continued their unbeaten run with a classy 52-27 win over Bath on Saturday, going six points clear at the top of Pool Three.
Pool Four is very tight with Ulster, Leicester and Clermont Auvergne separated by just three points after four matches.
Ulster defeated Aironi 46-20 on Saturday to go top with 14 points and Leicester overcame a nine-point deficit against Clermont to win 23-19 in a pulsating game that lifted the English side to second place, two points behind the leaders.
The fifth round of Heineken Cup games will be played over the weekend of Jan. 13-15.