AC Milan crashed out of the Europa League as Konstantinos Fortounis' late penalty claimed a 3-1 win for Olympiacos, sending the Greek side through to the knockout stages.
Gennaro Gattuso's men required just a point to secure progression from Group F, but they found themselves behind when Pape Abou Cisse headed in on the hour.
With Milan's defence rocking, Olympiacos grabbed a crucial second goal when Cristian Zapata deflected Guilherme's hopeful strike into his own net nine minutes later.
Zapata immediately made amends when he bundled the ball in at the other end to make it advantage Milan courtesy of their improved head-to-head record, but, after Ignazio Abate was penalised for holding onto Vasilis Torosidis, Fortounis kept his cool to book Olympiacos' place in last 32.