While the odds of overturning a 4-1 first leg defeat in the Champions League are slim at best, there will be a part of Barcelona thinking "what if" as the dust settles on their last-16 exit at the hands of Paris St-Germain.

Lionel Messi scored a stunning equaliser to make it 1-1 on the night in Paris, but his penalty was saved on the stroke of halftime with the scores level, meaning what could have been a blockbuster second half turned into a non-event.

Remarkably, it was the 28th penalty the Argentine has missed in his career - had he scored it would have been his 100th successful attempt - and it is perhaps the only weakness in his formidable armoury.

More than the number of misses, it is perhaps the size of the games that they occur in that sets alarm bells ringing.

Messi rattled the bar against Chelsea in the 2012 Champions League semi-final, blasted over for Argentina against Chile in the 2016 Copa America final and had an effort saved in a disastrous draw with Iceland at the 2018 World Cup.

He also missed a penalty in Barca's 2-2 draw with Valencia in December, albeit sparing his blushes by heading in the rebound.

While Messi's courage and willingness to step up and take penalties must be admired, the 33-year-old never truly looks comfortable from the spot, despite his considerable gifts, and his big game record points to that.

The problem facing Barcelona, however, goes further.

Martin Braithwaite, Antoine Griezmann, Ousmane Dembele and Miralem Pjanic have all missed a penalty each on top of Messi's two, with Barca failing to net six of the 15 they have taken.

Whether Messi remains or leaves the Camp Nou at the end of the season remains to be seen, but Barca's issues from the spot should also be on the agenda and need to be addressed.