Motherwell's hopes of reaching the Champions League group stages are hanging by a thread after Panathinaikos inflicted a 2-0 defeat on the Scottish side at Fir Park.
A crowd of 9,035 were in attendance as the Well made their elite European debut in the first-leg third qualifying round match.
The home support's enthusiasm was damped on 13 minutes when Lazaros Christodoulopoulos's inswinging free-kick found its way inside Darren Randolph's far post.
Substitute Charis Mavrias doubled the Greeks' advantage with a fine breakaway goal 14 minutes from time.
The second leg will take place on August 8 at the Olympic Stadium in Athens.