Grenoble have held off a strong recovery from Agen to secure a 40-20 victory over their fellow Top 14 side in Pool 5 of the European Rugby Challenge Cup.
The visitors were looking to enhance their challenge in the group, and they got off to the perfect start as it took less than a minute for Xavier Mignot to crash over and record the first score.
Sona Taumalolo scored the first of his three tries on the night after 12 minutes to extend the early lead, and veteran Tongan added his second before the half-hour, with Agen's only response coming in the form of a Bautista Guemes penalty.
The 34-year-old completed a first-half hat-trick six minutes later to secure the bonus point and give Grenoble a 25-point lead at the break, but Agen launched a remarkable fightback in the second half to move to within eight.
First Marc Baget went over to cut the deficit, before Marc Barthomeuf and Marius Deguilhem scored as the hosts threatened to complete the most unlikely of comebacks.
However, it was not to be as a penalty try and a second score from Mignot secured a 40-20 victory for Grenoble to ensure that they kept up the pressure on Edinburgh and London Irish in Pool 5.