Yiadom started the scoring before the hosts drew level but he restored his side's lead in the 70th minute.
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Before he put Nenad Milijas through to make it 3-1 for the visitors after six minutes.
Floriana reduced the deficit in the 78th minute through Maurizio Vella and then Red Star were reduced to ten men after Marko Gobeljic saw red.
Four minutes from time, Ignacio Varela snatched the equalizer and then got send off a minute later.