West Ham were 2-0 up on their Romanian visitors at Upton Park in the first leg of their third qualifying round tie thanks to goals from Enner Valencia and Mauro Zarate yesterday.
But James Collins then became the Hammers' third player to be sent off in five games under new coach Slaven Bilic and the Romanians took full advantage with Fernando Boldrin and an own-goal from debutant Angelo Ogbonna levelling the tie.
Southampton brushed aside Dutch club Vitesse Arnhem 3-0 thanks to goals from Italian Graziano Pelle, Serbian Dusan Tadic, from the penalty spot, and a late third from Shane Long.
The Saints' manager Ronald Koeman is a former Vitesse coach while the win was the English side's first in Europe in 34 years.
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One of the big surprises of the evening took place in Italy where Sampdoria were taken apart 4-0 by Serbia's Vojvodina which gives the Serie A side a mountain to climb in the return leg next week.
The defeat was Sampdoria's heaviest European loss since 1962.
Borussia Dortmund began life without departed coach Jurgen Klopp with a 1-0 win away to Austrian outsiders Wolfsburg to give new boss Thomas Tuchel a winning competitive start.