January transfer window failed to materialise as Europe's top clubs largely kept their powder dry.
A KrisCommons header gave former European champions Celtic a 1-0 win over Swedish side Elfsborg Boras while Fenerbahce made the most of their Champions League lifeline with a 1-1 draw against Salzburg in the first leg of their third qualifying round tie on Wednesday.
Four-time European Champions Ajax Amsterdam were felled at the first hurdle of the continent's second tier Europa League on Thursday, exiting in the group stage two days after rivals PSV Eindhoven celebrated long-awaited success.
Napoli's Marek Hamsik enjoyed a memorable return to his former club Slovan Bratislava, scoring one and creating another, in a 2-0 victory on Thursday as the Italians joined five others who made it two wins from two in the Europa League group stage.
Images from Champions League matches played across Europe on Tuesday
Jonatan Soriano's love affair with the Europa League continued as last season's top scorer grabbed a hat-trick on Thursday to help Salzburg become one of four teams to reach the knockout stages.
Last-minute starter Adrian Ramos scored a first-half header to give Borussia Dortmund a 1-0 victory over Sporting on Wednesday and earn a spot in the knockout stage of the Champions League with two Group F matches to spare.
Goals from Jan Vertonghen and Jermain Defoe left Tottenham Hotspur on the cusp of the Europa League knockout stages as four other clubs maintained perfect starts on Thursday.
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Photos from the Champions League matches played across Europe on Tuesday