Five-times winners Liverpool reached the Champions League proper after a Dirk Kuyt goal deep into extra time gave them a 1-0 aggregate win over plucky Belgian rivals Standard Liege on Wednesday.
The Dutch striker scored in the 118th minute to the relief of the Anfield faithful as Liverpool, who last won the trophy in 2005, struggled to find a way through.
"It wasn't a good performance but we always know we have the quality to score," Kuyt, who brilliantly turned Ryan Babel's left cross in at the far post, told ITV.
Former winners Olympique Marseille also looked below par against Brann Bergen but two goals from Mamadou Niang sealed a 2-1 home win for a 3-1 aggregate victory over the Norwegians.
In contrast, Arsenal romped to a 6-0 rout of Dutch side Twente Enschede, coached by former England manager Steve McClaren, after Samir Nasri, William Gallas, Theo Walcott and Nicklas Bendtner handed them a 4-0 second-leg win at home.
They were joined by other big guns and three teams that qualified for the lucrative group stage of the competition for the first time.
Atletico Madrid beat Germany's Schalke 04 4-1 on aggregate after crushing them 4-0 at home, Dynamo Kiev steamrolled to an 8-2 overall demolition of Spartak Moscow and Fiorentina eased to goalless draw at Slavia Prague after a 2-0 first-leg win.
Sergio Aguero, back from helping Argentina win the Olympic gold medal, cancelled out Schalke's 1-0 lead from the first leg before goals by Diego Forlan, Luis Garcia and Maxi Rodriguez sealed Atletico's passage at their Vicente Calderon stadium.
Danish champions Aalborg, Cypriots Anorthosis Famagusta and Belarus surprise package BATE Borisov enjoyed the unprecedented success of advancing past the preliminary rounds into Thursday's group stage draw in Monaco.
Anorthosis went down 1-0 away to Olympiakos Piraeus but upset the Greek side 3-1 on aggregate after a stunning 3-0 win in the first leg.
Aalborg brushed aside Kaunas 4-0 after a Kasper Risgard double gave them a 2-0 away win over their nine-man Lithuanian rivals, who had Mindaugas Grigalevicius sent off after half an hour and Linas Pilibatis shown the red card in the 67th minute.
BATE held on for a 1-1 draw at home to Levski Sofia after upsetting the Bulgarians 1-0 a fortnight ago.
There was mixed success for Turkish teams as Fenerbahce squeezed past Partizan Belgrade 4-3 on aggregate while bitter Istanbul rivals Galatasaray bowed out with a 3-2 overall defeat by 1986 European champions Steaua Bucharest.
Headers by Semih Senturk and Brazilian forward Alex gave Fenerbahce a 2-0 lead in front of their vociferous fans before Zoran Tosic set up a nervy finish with a superb free kick.
Banel Nicolita struck in the 57th minute to send Steaua through and give Romanian fans plenty to cheer about after the country's champions CFR Cluj qualified automatically.