Former champions Eintracht Frankfurt threw away a two-goal lead in the final minutes as they were held 3-3 by Viktoria Plzen in their Europa League opener on Thursday. Prince Kwabena Adu netted in the 86th off Vaclav Jemelka who then smashed the improbable equalizer into the roof of the net in the third minute of stoppage time. Frankfurt goalkeeper Kaua Santos, standing in for German international Kevin Trapp, did not look good on both occasions. The hosts took a deserved lead on a rainy night in the 38th minute when in-form Hugo Ekitike fired into the bottom right corner. It was his fourth go…