Leicester left it very late to beat Montpellier as they snatched a vital 15-14 Heineken Cup win at the Stade Yves-du-Manoir.
After the eight-try thriller between the two sides the previous week the return match was scoreless for 50 minutes until Tom Youngs crossed for the visitors.
Two tries in 10 minutes from fly-half Enzo Selponi and wing Lucas Dupont looked to have secured Montpellier the win before the late drama.
A converted try from Leicester centre Niki Goneva 45 seconds from time kept them in touch with Pool 5 leaders Ulster, with a nerveless Ryan Lamb kicking the match-winning conversion.
Harlequins continued to snap at the heels of Clermont Auvergne as they kept alive their hopes of reaching the quarter-finals by grinding Racing Metro into submission.
Twickenham Stoop hosted a poor spectacle and Quins will be disappointed to have finished a match they dominated without going close to posting a try-scoring bonus point as the game ended 17-3.
But a second win in Pool Four leaves them only four points below leaders Clermont with the French giants having to visit London in January.
Nick Evans, instrumental to last weekend's 32-8 victory in Nantes, was equally influential in the home leg of the double-header as Quins established a 14-0 half-time lead.
The 33-year-old kicked three penalties and laid the groundwork for Racing's defeat until a shoulder injury forced his exit at half-time.
Wing Charlie Walker crossed just seconds before the break, but that was the only time Racing's whitewash was breached with Quins guilty at times of trying to play too much rugby in wet conditions.
Gloucester's quarter-final hopes were left hanging by a thread after underdogs Edinburgh stunned them at Kingsholm.
Edinburgh had lost nine of their previous 10 games in Europe, but centre Ben Atiga's second-half try and 11 points from the boot of full-back Jack Cuthbert left Gloucester reeling.
It means the west country club are five points behind Pool Four leaders Munster before they host the Irish heavyweights next month, with Edinburgh and Perpignan likely to be scrapping for minor placings.
Gloucester's erratic Aviva Premiership form surfaced at exactly the wrong time on a European stage as they struggled to subdue an Edinburgh outfit high on commitment and endeavour.
Gloucester claimed a 35th-minute penalty try converted by fly-half Freddie Burns, who also kicked a penalty, but they could have few complaints over a 16-10 loss as Edinburgh posted a first Heineken Cup away win since they toppled Racing Metro in January 2012.