Jose Mourinho's Chelsea earned much-needed relief from their domestic woes, beating his former club Porto 2-0 to top Champions League Group G and move into the knockout stage.
An own goal and one from Willian ensured victory for the struggling English champions and sent Porto into the Europa League.
Chelsea, cheered by a beaming owner Roman Abramovich, looked a different side from the one that have slumped to eight domestic defeats in 15 league games, including four at home.
The result takes the pressure off Mourinho after intense speculation that the coach, who has won the Champions League with both Porto and Inter Milan, might lose his job if Chelsea failed to qualify for the knockout stages.
Olivier Giroud grabbed a hat-trick as Arsenal crushed Olympiakos Piraeus 3-0 to book their spot in the last 16 with a classy demolition job that ended the hopes of their Greek opponents.
With Arsenal needing an emphatic victory to make it out of Group F, France forward Giroud produced a high-calibre display of finishing to ensure the English club finished second, level on nine points with Olympiakos, but ahead by virtue of their better head-to-head record.
The victory completed a remarkable turnaround in fortunes for Arsenal who lost three of their first four games of the campaign and needed to win by any result other than 1-0 or 2-1 in their decisive group clash to finish second behind group winners Bayern Munich.
Teams qualified for the last 16 of the Champions League.... Real Madrid, Paris St Germain, VfL Wolfsburg, PSV Eindhoven, Atletico Madrid, Benfica, Manchester City, Juventus, Barcelona, Bayern Munich, Zenit St Petersburg, AS Roma, Arsenal, Chelsea, Dynamo Kiev and Ghent.
The draw will be made next week.