A brilliant performance from Swansea saw the English Premier League side sweep aside Valencia in their Europa League group game, as Tottenham, Sevilla, Fiorentina and Lazio also won.
There was a shock defeat for Dutch giants PSV Eindhoven, who went down to Ludogorets, while Eintracht Frankfurt proved their credentials with an impressive 3-0 result against French side Bordeaux.
At the Mestalla, Valencia were expected to give Swansea a tough time, but it proved to be the opposite as Michael Laudrup's men impressed, albeit with Valencia down to ten men after just 10 minutes.
Adil Rami saw a straight red card after bringing down Swansea striker Wilfried Bony while through on goal.
Swansea took full advantage of being a man up with the Welsh side taking just four minutes after the dismissal to score.
Michu created the goal by breaking down the left before finding his strike partner Bony, who managed to find the back of the net via a deflection.
It was all Swansea really from there as Valencia, who have struggled in the La Liga this season losing three out of their four games, failed to cope being a man down.
It did take the Premier League team until the 58th minute to double their lead, though, with Michu getting in on the scoresheet after being put through by Alejandro Pozuelo.
Jonathan De Guzman added the gloss four minutes later with a wonderful freekick from 30 yards as Swansea eased to their first win.
At White Hart Lane, it was quite straightforward for Spurs, who posted a comfortable 3-0 victory over Norwegian outfit Tromso.
Jermain Defoe scored a brace in the win with the third goal coming from Christian Eriksen, a brilliant strike from the edge of the box.
The win did come at a cost for Tottenham, though, with three players - Danny Rose, Mousa Dembele and Younes Kaboul - forced off with injuries.
Rose had to be substituted in the first half after the left-back picked up what seemed like a hamstring injury, while Dembele was stretchered off.
Kaboul then added to Villas-Boas' worries with another two games coming up in no time, by limping off late in the game with Spurs having already made all three of their substitutions.
The other British side in the tournament, Wigan, who entered the Europa League courtesy their F.A. Cup win last season, drew 0-0 with Zulte Waregem.
The surprise result of Thursday was PSV's loss to Bulgaria side Ludogorets, who won 2-0 thanks to goals from Roman Bezjak and Virgil Misidjan.
Results: Valencia 0-3 Swansea City; St Gallen 2-0 FC Kuban Krasnodar; Dinamo Zagreb 1-2 FC Chornomorets; PSV Eindhoven 0-2 Ludogorets; FC Salzburg 4-0 Elfsborg; Standard Liege 1-2 Esbjerg; Zulte Waregem 0-0 Wigan Athletic; Maribor 2-5 Rubin Kazan; Fiorentina 3-0 Pacos de Ferreira; Pandurii 0-1 FC Dnipro Dnipropetrovsk; Eintracht Frankfurt 3-0 Bordeaux; Maccabi Tel-Aviv 0-0 APOEL; Dynamo Kyiv 0-1 Genk; FC Thun 1-0 Rapid Wien; Freiburg 2-2 FC Slovan Liberec; Estoril 1-2 Sevilla; Real Betis 0-0 Olympique Lyon; Vitoria Guimaraes 4-0 HNK Rijeka; Apollon 1-2 Trabzonspor; Lazio 1-0 Legia Warsaw; Sheriff FC 0-0 FC Anzhi Makhachka; Tottenham 3-0 Tromso; PAOK 2-1 Shakhter Karagandy; Maccabi Haifa 0-1 AZ Alkmaar.