Panathinaikos lifted the Greek Cup on Saturday, beating local rivals Olympiakos 3-1 to complete the first leg of a possible domestic double.
A second-half brace from Cyprus international Michalis Konstantinou saw off Olympiakos who were on level terms for only three minutes.
The match was dominated by a series of quick-fire substitutions from Olympiakos's veteran coach Nikos Alefantos who began making changes after only 15 minutes.
He responded to Panathinaikos taking the lead through a Dimitris Papadopoulos header by bringing on a second forward, Lambros Houtos for defender Grigoris Georgatos.
He then withdrew centre back Spyros Vallas for winger Dimitris Mavrogenidis.
Panathinaikos were unfortunate not to extend their lead before the break. Konstantinou was particularly guilty with two bad misses.
Alefantos replaced substitute Houtos with Polish forward Kouzba at the interval.
Against the run of play Olympiakos grabbed an equaliser after Brazilian forward Giovanni got his head to an excellent Predrag Djordjevic cross.
Parity was shortlived as Konstantinou made up for his first-half misses with his two goals.
Greece forward Papadopoulos again underlined his claims for a starting place at Euro 2004 next month with an excellent knock-on for the Cypriot who got in front of the defence to slot home in the 68th minute.
A mistake by Christian Karembeu, playing as a makeshift centre back, let Konstantinou through to seal the result in the 80th minute.
With a two-point lead over Olympiakos in the league, Panathinaikos now hope to complete the double.