It was that sort of night as Liverpool were left counting their bruises, as well as their blessings, on their way to a last eight date with Porto.
As the confusion and ugly mood continued, Roma midfielder Damiano Tomassi was sent off for a second bookable offence and Vincent Candella was fortunate not to follow him after appearing to push Robbie Fowler in the face.
If Gerard Houllier felt luck was on Liverpool's side a week ago, when they soaked up early pressure and hit back with Owen's goals, it was nothing compared to last night.
With Owen missing a 61st-minute penalty and Guigou then putting Roma in front, another goal just 12 minutes from the end of normal time would surely have finished off shell-shocked Liverpool, who were already on the ropes.
In a bad-tempered, niggly and, at times, downright nasty battle, Liverpool always looked on edge.
Roma forced the pace throughout and should have increased the home side's unease in the 20th minute when Marco Delvecchio dragged a glorious chance wide.
Liverpool briefly threatened as Christian Ziege's inswinging 36th-minute free kick was stopped at full stretch by Francesco Antonioli, while Owen blazed wide two minutes later. The striker should have settled matters after Jonathan Zebina bundled Emile Heskey off the ball and was penalised in the 61st minute.
But, with England coach Sven Goran Eriksson looking on, there was an ominous lack of conviction about the way Owen approached the spot-kick and Antonioli read his intentions with ease, saving comfortably to his right.
Owen's misfortune merely heightened the mounting anxiety which was in danger of developing into full-scale panic when Guigou strode forward in the 70th minute to beat Sander Westerveld from 25 yards. There was always an intimidating undercurrent and eventually it spilled over. Garcia-Aranda Encinar was close to losing control as enraged Roma players milled round him menacingly after the penalty about-face.
The eccentric Spaniard resorted to flourishing a succession of yellow cards to restore order and in the 85th minute, banished Tommasi for a second booking.
FC Porto, who progressed 3-2 on aggregate despite losing 2-1 in Nantes last night, had midfielder Dmitri Alenitchev sent off seven minutes from time.
