Egeman Korkmaz's second-half header gifted Fenerbahce a hard-fought 1-0 Europa League win as Jorge Costa's first match in charge of AEL Limassol ended in defeat.
Former SC Braga and CFR 1907 Cluj boss Costa was given little time to prepare for this fixture after only being announced as the Cypriot side's new coach yesterday.
And although the hosts performed admirably for the Portuguese it was all in vain as Korkmaz headed home from Cristian Baroni's corner to send the Turkish outfit top of Group C.
It could prove to be a priceless victory for Fenerbahce, who are three points clear of German side Borussia Monchengladbach and French outfit Marseille.
Costa would have been hoping to extend his new side's unbeaten run at home in this competition but the visitors started well, with Cristian Baroni testing AEL goalkeeper Matias Degra with an early sighter from 25 yards while former Liverpool striker Dirk Kuyt struck wide from just outside the area.
At the other end, Melo Rui Miguel was causing all sorts of problems for the Fenerbahce defence and twice went close but failed to work keeper Volkan Demirel on both occasions.
The Portuguese midfielder was then denied by a fantastic block from Hasan Ali Kaldirim while Demirel had to be at his best to parry away Jorge Felipe Monteiro's effort as Limassol ended the half with a flourish.
The hosts picked up where they left off after the interval with Rui Miguel forcing Demirel into another fine save although Kuyt narrowly shot wide soon after.
In such a tight game it was always likely one goal would be enough and it came in the 72nd minute when Baroni's flighted corner was headed into the net by Korkmaz.
Monteiro forced Demirel into another fine save shortly before the end but Fenerbahce held firm to secure the three points.