 Complete the following phrase:  Debrecen played their home matches between 1989 and 2014 at the Oláh Gábor utcai Stadion, which has a capacity of 12,500. After winning the first Nemzeti Bajnokság I trophy, it was found that the stadium did not meet UEFA stadium criteria. Therefore, the most important UEFA Champions League and UEFA Europa League matches had to be played at the 