#3 Lautaro Martinez
Inter Milan forward Lautaro Martinez has failed to deliver in the Champions League this season despite his reputation for being one of the best in the business. The Argentine has garnered huge attention from top European clubs after developing as a top sharpshooter with Inter.
Martinez is yet to make any kind of impact in the Champions League, though. The 24-year old had zero goals and zero assists in the group stage, which was unexpected from him considering his stellar form in Serie A.
He has racked up eight goals and two assists in the Italian top flight this season. However, the striker flopped in Europe as veteran Edin Dzeko was the one with all the tricks in the final third.
Although Inter qualified for the Champions League knockouts, Martinez's poor performance will be a major concern for them.
#2 Neymar
Lionel Messi's arrival was supposed to make things easier for Neymar at PSG. Surprisingly, that has not been the case for the Brazilian, who has been a shadow of his illustrious self so far this campaign.
Neymar had nothing to show for in four Champions League games this season, failing to connect with his attacking colleagues, Kylian Mbappe and Lionel Messi. The 29-year-old has endured a difficult start to his campaign, not just in Europe but also in the French top flight.
Manager Mauricio Pochettino is still trying to get the best out of Neymar and PSG's famed attacking trio. The winger remains a key piece in the PSG puzzle, but has failed to light up Ligue 1 or the Champions League this campaign. His poor form will be a major headache going forward if he continues to disappoint.
#1 Memphis Depay
Memphis Depay's first season at Barcelona is turning out to be a disappointing affair despite his bright start. The Dutchman was one of the bright spots for Barcelona initially, bagging eight goals and two assists in La Liga.
However, Depay has been poor in the Champions League, where the Blaugrana needed him the most. The forward had no involvement in any of Barcelona's goals in this season's Champions League, failing to be decisive in the final third.
Although Depay is not to be sublime and dominant, he has struggled for consistency this season. The 27-year old's zero impact in the Champions League meant Barcelona have dropped to the Europa League after a third-place finish.