Olympiakos moved into the driving seat to reach the Champions League Group Stage after a header by Togolese midfielder Alaixys Romao in extra time helped them win Croatia champions Rijeka in front of 32,000 fans at Georgios Karaiskakis Stadium on Wednesday night.
The Croatian team went ahead after a strike by Brazilian forward Herber just before half-time, but the Piraeus side leveled the match at the 66th minute with an emphatic goal by Belgian midfielder Vadis Odjidja-Ofoe.
Rijeka went down to 10 men when Leonard Zhuta received a second yellow card seven minutes from time. Romeo scored the winner from close range for the Greek champions, who had also hit the bar moments earlier.
The two sides will meet for the second leg of their Champions League playoff in Croatia on August 22.