ST. PETERSBURG, Mar 19 (SW) - Narrow margins sent Russian side Zenit St. Petersburg and Bulgaria's Levski Sofia through to the UEFA Cup quarter-finals on Thursday while Basel had a more comfortable go of things as they moved on.

Zenit St. Petersburg - Marseille 1-1
Zenit win 2-1 on aggregate

Marseille reserve goalkeeper Cédric Carrasso made a disastrous appearance and his error cost Marseille a spot in the UEFA Cup quarter-finals as Zenit progressed by a narrow margin.

With Zenit still ahead in the tie after their first-leg win in France, a shot by Alexander Kerzhakov looked tame enough for Carrasso to handle, but the ball slipped right through his hands and slowly rolled into the net to extend Zenit's lead.

Five minutes later, Frédéric Déhu got a crucial goal for the visitors when he blasted home, leaving Marseille needing just one goal without reply to advance, but all hope was gone when they were reduced to ten men as a frustrated Carrasso was dismissed for a foul on a streaking Kerzakov outside the area.

Levski Sofia - Udinese 2-1
Levski win 2-1 on aggregate

After a scoreless first leg at the Stadio Friuli, it was Udinese who took advantage in the 22nd minute with Fernando Tissone pushing the ball into the net after Levski couldn't clear a free kick by the visitors. The away goal left Levski needed two goals without reply to move on.

Six minutes into the second half, Daniel Borimirov got one of those goals for Levski with a nice finish after being set up by a fine Lucio pass.

The tie then swung in favor of the home side on 63 minutes when Igor Tomasic got his head to a cross by Lucio and beat goalkeeper Morgan De Sanctis to give Levski one foot in the quarter-finals.

Udinese pushed forward in search of the goal that would send them through, but the Bulgarians held firm and marked their deepest ever progress in a European competition.

Strasbourg - Basel 2-2
Basel win 4-2 on aggregate

Basel put the tie seemingly out of reach just three minutes in as Eduardo put the ball into a vacant goal after Mladen Petric laid the ball off to him when he could have easily had a crack at goal.

Eight minutes later, Rudy Carlier hit a header beyond Pascal Zuberbühler to give the home side a glimmer of hope, but Eduardo struck his second of the match in the 26th minute with a powerful volley shot.

A late goal by Cédric Kanté pulled Strasbourg a bit closer, but the result had already been decided as the Swiss side moved on to the final eight.