Another header in the 40th minute gave Fenerbahce a 2-1 lead with Hungarian central defender Attila Szalai the scorer.
In the 45th minute of the first half, Valencia was fouled in the Kasimpasa area and Fenerbahce were awarded a penalty kick.
Valencia converted the penalty successfully to the make the score 3-1 for Fenerbahce.
Near the end of the second half, Hajradinovic had a through ball on a quick counterattack as he dribbled the ball into the Fenerbahce area. Tekin left his goal to tackle him but fouled the Kasimpasa midfielder.
Tekin was shown a yellow card for his mistimed tackle. Kasimpasa's Kosovan right back Florent Hadergjonaj scored from the white spot, making it 2-3. But Fenerbahce secured the win to pursue league leaders Besiktas.
The 2020-21 Super Lig title race has been relentless between Besiktas and Fenerbahce. Second-place Fenerbahce have 72 points in 35 matches. Besiktas have 75 points to top the division. Galatasaray are in third place with 69 points. The Super Lig season will end in May as only five games are left.
Genclerbirligi - Caykur Rizespor: 2-1
Ittifak Holding Konyaspor - Atakas Hatayspor: 0-0
Trabzonspor - Fatih Karagumruk: 2-0
Yukatel Denizlispor - Demir Grup Sivasspor: 1-1
Besiktas - Hes Kablo Kayserispor: 3-1
Fraport TAV Antalyaspor - Galatasaray: 0-1
Helenex Yeni Malatyaspor - MKE Ankaragucu: 2-1
Gaziantep - Buyuksehir Belediye Erzurumspor: 2-3
Medipol Basaksehir - Aytemiz Alanyaspor: 0-0
Fenerbahce - Kasimpasa: 3-2