Tottenham blew a two-goal advantage to draw 2-2 in their first UEFA Champions League game of the season.
Harry Kane and Lucas Moura had put the English club on a pedestal of victory, but a determined Greek side came back to draw level.
Harry Kane opened scoring via a penalty in the 26th minute after he was tripped in the box by Meriah and a VAR check confirmed the kick.
Lucas Moura doubled the advantage on the half hour mark when he rifled a shot in from 20 yards after Ben Davies gained posession and laid it on a plate for the Brazilian.
Daniel Podence was able to pull one back before the break as he played a brilliant one-two and quickly found himself through on goal steadying himself before rifling into the far corner past goalkeeper Lloris.
Olympiacos also got their own penalty advantage and it was awarded after a VAR review. Mathieu Valbuena puts the penalty to Lloris' right, sending his fellow Frenchman the wrong way.
Tottenham kept the pressure and a chance came when Son whipped a cross in after some neat footwork but there was no one in the 18-yard box to meet it and turn it in.
Five minutes was added but that was not to change the result as it ended 2-2 at the Karaiskaki Stadium.