In the 21st minute, Ruslan Malinovsky got the curtain raiser with a left-footed free kick for the visitors but the 19-year-old winger pulled one back for the Ghelamco Arena outfit, six minutes later.
The game quickly turned on its head as efforts from Omar Colley, Mbwana Samata and Jere Uronen ensured Albert Stuivenberg’s men pulled 4-1 away from their Belgian Pro League rivals in the first half.
Just after the hour mark Kalifa Coulibaly halved the deficit for the Buffalos who were made to rue their chance of staging a comeback after Jeremy Perbet missed a penalty, won by the enterprising Kalu, minutes later.
Tanzania marksman, Samata, registered a brace soon, to make the scoreline 5-2. Simon Moses and Rabiu Ibrahim both came off the bench but could offer little.
Gent, who also lost Anderson Esiti to a second booking, now have to overturn a heavy deficit when they visit the Luminus Arena for the second leg of the tie on March 16 so as to progress to the quarter-finals of the competition.