Jahanbakhsh smashed home from inside the box with 14 minutes left on the clock on his debut at the competition as Feyenoord defeated nine-man Celtic 2-0 at home to go top of Group E.
Calvin Stengs got the Dutch champion off the mark deep into stoppage time in the first half before Celtic’s Gustaf Lagerbielke and Odin Thiago Holm received their marching orders in the space of five minutes after the interval.
Lazio and Atletico played to a 1-1 draw in Rome in the other match of the group.
In Hamburg’s Volksparkstadion, Taremi scored a third goal for Porto, tapping in with a delicate effort on the half-hour mark, to help Porto beat Shakhtar Donetsk of Ukraine 3-1 in Group H.
Brazilian Galeno scored twice either side of a Kevin Kelsy’s equalizer for the Ukrainian side.
Elsewhere in the group, Joao Felix bagged a brace as Barcelona thrashed Belgian club Antwerp 5-0 at home.