Legia had just taken a 2-1 lead in the first leg of the third qualifying round tie when their player Ondrej Duda was hit by a stone thrown from the stand.
Play was immediately suspended as Duda was taken off the field on a stretcher and had his head bandaged, but he was soon back on his feet and even changed his bloodied shirt in anticipation of a restart which never came.
A post on Legia’s official Twitter account read: “The game in Tirana is suspended. Ondrej Duda was hit with a stone by Kukesi fans…”
Ten minutes later, they added: “Official: the FK Kukesi – Legia game is ended. It will be probably declared forfeit, as Duda was hit with a stone by Albanian fans.”
It is the second consecutive season that Legia’s European participation has been marked by controversy.
They were thrown out of last season’s Champions League campaign for fielding an ineligible player during a 6-1 aggregate win over Scottish champions Celtic.
UEFA confirmed that they will wait to receive the official reports before ruling on the incident.
“We are waiting for the reports from the officials (to be) evaluated,” they said.