Kostas Mitroglou's fantastic goal turns the match in Athens completely around.
Iannis Maniatis takes full advantage of some ponderous defending by Aaron Ramsey to draw Olympiacos level.
One thing worth pointing out is the excellent atmosphere Olympiacos fans are creating. They love their football in Greece - take a look at the welcome Olymipacos supporters gave to new signing Albert Riera few years back.
A neat side-foot finish from Rosicky puts Arsenal ahead against Olympiacos.
Arsenal had an early opportunity to take the lead in Athens, but Aaron Ramsey's boot only found fresh air.
Best of luck to Arsenal's debutant midfielder Jernade Meade, who starts in Athens tonight. But he may want to watch out for his opposite number, Olympiacos defender Iannis Maniatis, who's a bit...ummm...crazy?
Arsenal will be pretty keen for a repeat performance of their previous clash with Olympiacos, a 3-1 win over the Greeks at the Emirates in October.