Arsenal: Laurent Koscielny
Arsenal's attacking talent is plentiful, and the addition of Mesut Ozil, the brilliant German schemer, only adds to that number.
However, their achilles heel at the top level has long been a disappointing defence, and with Arsene Wenger having chosen to forego improvements in that area this summer, then Laurent Koscielny will need to continue what has been, on a personal level, an excellent 2013.
The French defender has been consistently brilliant this calendar year, showcasing decisiveness, solid tackling and a wonderful reading of the game which often allows him to sweep up danger before it presents itself.
With Arsenal having been placed in the Group of Death, the 27-year-old will need to be at his most combative if the Gunners are to emerge successful.
Marseille: Andre-Pierre Gignac
After a bitterly disappointing 2011-12 where he netted just once in 21 league games and was largely frozen out by then-manager Marseille manager Didier Deschamps, Andre-Pierre Gignac appeared to have little future at the Stade Velodrome.
Fast forward to the present day and the 27-year-old striker is very much first choice under Elie Baup, having played a key part in Marseille's second-place finish in Ligue 1 last season with 18 goals in all competitions.
Not the most mobile of strikers, nor the most glamorous, Gignac's beauty is in his simplicity: ball comes in, he keeps it, finds a teammate and looks to head to the box. Powerful and bullish, he doesn't mind combating defenders and is always looking to get a shot off towards goal.
And on the back of last season, Gignac has continued the present campaign in a similar manner, with three goals in his first four Ligue 1 outings. With supply from the likes of Andre Ayew and new signing Florian Thauvin, Gignac will be a dangerous proposition.
Borussia Dortmund: Robert Lewandowski
Perhaps the outstanding No. 9 in European football last season, Robert Lewandowski remains at Borussia Dortmund this term, ready to spearhead Juergen Klopp's side on another European charge.
Die Borussen produced some of Europe's most magical and aesthetically pleasing football last time out as they went all the way to Wembley with the Polish star at the heart of their success.
The highlight of his season was undoubtedly his four-goal haul in BVB's semi-final win over Real Madrid at the Westfalenstadion, a match which showcased the very best of Lewandowski: his deftness of touch, intelligent movement, determination, composure and clinical finishing.
The 25-year-old finished with 36 goals in 49 games in 2012-13—10 of which came in Dortmund's run to the Champions League final—and sides will be well aware of his capabilities ahead of the upcoming campaign; stopping him, however, is a completely different matter.
Napoli: Marek Hamsik
Having seen Ezequiel Lavezzi and Edinson Cavani leave in successive summers, Marek Hamsik is the last tenor left in Naples, but the Slovakian makes a return to the Champions League following Napoli's absence last time round.
Walter Mazzarri and the 3-4-3 formation have gone also, with European Cup-winning coach Rafa Benitez and his preferred 4-2-3-1 formation coming in; indirectly Hamsik has been handed greater responsibility, given a central attacking role behind new striker Gonzalo Higuain.
And so far, the 26-year-old is thriving under Benitez, with four goals in his opening two games of the Serie A season—coming on the back of 11 goals and 18 assists in the league last season.
A mixture of excellent vision, clever passing, hard work and intelligent, well-timed off-the-ball runs, Hamsik is very much the modern day all-action attacker, a powerful No. 10, which Italian football has been embracing over the last 12 months.
Under his new manager Hamsik has added greater incision to his game already, his versatility proving a great strength also. Napoli, the most dangerous of all the fourth seeds, look well set to compete in the Group of Death, and Hamsik could prove their biggest danger.