Racing Metro ground out a victory despite being forced on to the back foot for much of their Heineken Cup Pool 4 clash with French rivals Clermont Auvergne.
All the points in the first half came through penalties, but Marc Andreu scored the game's only touchdown shortly after half-time to set up victory.
The result was harsh on Clermont winger Sitiveni Sivivatu, whoe was almost unplayable as his side dominated the territorial battle but could not put points on the board.
Morgan Parra kicked Clermont into the lead with a ninth-minute penalty.
The visitors were the better side in the opening exchanges, with Sivivatu at the heart of most of their best work, and doubled their lead with a second penalty in the 23rd minute.
Jonathan Sexton cut the deficit with a kick from just outside the 22 but Parra made it 9-3 at the interval.
But more good work by Sivivatu was wasted as Racing snatched the lead early in the second half.
The giant New Zealand international burst clear in midfield and sent his side away on the overlap - but the ball was turned over by Racing full-back Benjamin Lapeyre and scooped up by wing Andreu, who raced 90 yards to touch down before Sexton converted.
Some fluent handling by Clermont was brought to a halt as Andreu's tackle on Julien Pierre sparked a touchline fracas in which the try-scorer appeared to aim a kick at the Clermont lock, though no cards were issued.
Sexton added his second penalty to put his side 13-9 up and Parra was off target by the narrowest margin in reply, with the touch judges referring the decision to video referee Derek Bevan.
Lapeyre again forced a turnover, stripping the ball from Lee Byrne to prevent Clermont scoring following yet another Sivivatu break.
Clermont winger Napolioni Nalaga was sent to the sin bin after stretching out a knee to strike Andreu as his opposite number ducked into a tackle.
Andreu returned to play his part in a desperate rearguard as Racing held up Clermont's final drive through multiple phases in their own 22 to cling on to victory.