Lech Poznań beat Wieczysty Kraków 2-1 in punishing heat, giving the Polish champions their first win since being knocked out of Champions League qualifying by Danish side Aarhus on penalties.
The match was played in conditions significantly above 30 degrees Celsius with high humidity. Players from both teams dropped to the turf at the final whistle. Frederiksen told the squad in the dressing room afterwards that he had never seen anything like it.
Midfielder Radosław Murawski had approached Frederiksen on the pitch and told him he should ease his criticism because the coach had not felt how hot it was out there. Frederiksen acknowledged the conditions were extreme and said he could imagine they were hellishly hot.
Murawski later told Canal+ Sport that Frederiksen had shouted intensely at the players throughout the match because he demanded constant pressing, but the players sometimes simply did not have the energy for it. Lech also had 120 minutes in their legs from the Aarhus contest.
Lech next host KI Klaksvik of the Faroe Islands in the Europa League qualifying third round on 6 August, and then face Piast Gliwice in the Ekstraklasa on 9 August.
