Ghanaian winger Kamaldeen Sulemana opened his account for Rennes in the competition as they came back from behind to record a 2-1 win over Dutch side Vitesse.
Wittek opened the scoring for Vitesse in the 30th minute and the hosts were able to hold on to the lead for the rest of the first half.
In the second half, the visitors showed more drive and were rewarded with an equalizer courtesy an excellent finish from Guirassy from 12 yards.
Kamaldeen got in on the act to score in the 70th minute, ensuring his team's victory. He has scored four times and assisted once in 10 games for his team.