A late Gazelec Ajaccio own goal was to thank for giving Rolland Courbis his debut win as boss of Stade Rennais in Ligue 1.
A minute into added time, substitute, Roderic Filippe turned the ball into his own net under the pressure of Kamil Grosicki.
The match was Courbis' first as head coach of Rennes who had only won two matches at home going into the tie.
After only replacing Philippe Montanier a few days ago, Courbis set on changing what had been a dismal record at Roazhon Park this season.
First half flurry
Rennes started the best of the two teams and had the majority of the early chances, however none were clear cut. Romain Danze's long range effort coupled with Cheikh M'Bengue's deflected cross hitting the post was the best the hosts could muster at the start.
The best chance of the half did come to the left-back, M'Bengue, as he linked up well with Paul-Georges Ntep on thirteen minutes. The overlapping defender went one-on-one with the keeper, Clement Maury, but the stopper done enough to put him off as he sent the shot wide.
The goalkeeper, Maury, was lively throughout and was made to work on several occasions throughout the match. Youngster, Ousmane Dembele, headered the ball, following a free kick, towards the target but Maury done enough to stretch across goal and parry out.
At the other end, chances were few and far between, and the little Gazelec did have were passed up by John Tshibumbu. The striker would have been embarrassed with his best chance of the half when he turned a shot from the centre closer to the corner flag rather than the target.
Late goal ended sluggish second half
The second half was a more tedious affair. Both teams found it difficult to create any rhythm in their passing and there was a lack of promising chances.
Hearts were in mouths though when Gazelec's Damjan Djokovic had a shot from the edge of the box cleared almost off the line by Ntep.
The two goalkeepers both had to look lively a minute apart when Jerome Le Moigne for Gazelec and Giovanni Sio for Rennes were both denied by Benoit Costil and Maury respectively.
Gazelec thought they had done enough to salvage a point from a match in which they battled throughout. However, substitute, Filippe completely dented the fighting spirit the visitors had.
Polish winger and substitute, Grosicki, controlled a high pass with ease but was beaten to the shot by Filippe who knocked the ball into the far right post and it trickled over the line.
The win momentarily puts Rennes in third place in the Ligue 1 table whilst Gazelec Ajaccio remain on 13th position. Next week the victors play Bordeaux while the losers play Rolland Courbis' old club, Montpellier.