Sevilla witnessed first hand the chasm between UEFA Cup football and the Champions League on Wednesday with a humbling 3-0 defeat at Arsenal.
The Andalucians, winners of Europe's second-tier club competition for the last two seasons and tipped to make an impact among the big boys, were pulled apart at the Emirates with Cesc Fabregas, Robin van Persie and Eduardo da Silva scoring the goals for the silky Gunners.
Czech side Slavia Prague, the other debutants in action, had a more enjoyable baptism. They joined Arsenal on three points in Group H with a 2-1 home victory against Steaua Bucharest.
Seven of the eight matches in Groups E to H produced home wins with only Manchester United bucking the trend when Cristiano Ronaldo headed the winner for the English champions against Sporting Lisbon.
Barcelona, turned on the style in their Group E opener in the Nou Camp, Lionel Messi and Thierry Henry both on target in a 3-0 win for the Catalans against Olympique Lyon.
Perfect start
Champions Inter Milan began with a 1-0 defeat in Istanbul against Fenerbahce in Group G but Roma's perfect start to the season continued when they saw off Dynamo Kiev 2-0 in the Olympic Stadium. Francesco Totti and Simone Perrotta were on target in the club's 100th European victory.
Rangers came from a goal down to join Barcelona on three points in Group E, beating German champions Stuttgart 2-1 in Glasgow with goals from Charlie Adam and a Jean-Claude Darcheville penalty.
In a season in which the final will be staged in Moscow next May, Russia's only representatives, CSKA Moscow, went down 2-1 at PSV Eindhoven in Group G.
Optimism at Arsenal before the season was in short supply after Henry's defection to Barcelona but coach Arsene Wenger's new-look side have begun the season in dazzling fashion.
Fabregas was the chief tormentor of Sevilla. He opened the scoring when his shot took a huge deflection off Julien Escude and then set up second-half goals for van Persie and substitute Eduardo da Silva.
Wayne Rooney returned for Man United after breaking his foot, but it was Cristiano Ronaldo who stole the limelight with a diving header to earn United a valuable away win and was applauded off the pitch by the 40,000 crowd when he was withdrawn three minutes from time.
