After watching PSG limp to a 2-0 defeat at the Emirates Stadium back in October, nobody would've projected Luis Enrique's side to be merely two games away from the Champions League final six months on.
Arsenal's superiority was worryingly distinct, and the French club's issues in Europe certainly didn't dissipate in the aftermath. Entering the new year and with two league phase games remaining, PSG were outside of the top 24 and at risk of suffering an embarrassing early exit.
They then went 2-0 behind to a flawed Manchester City team on home soil, pushing their elimination closer, but Enrique's men have been on the up-and-up since. Their eventual 4-2 win over City set the wheels in motion for the club's rise to the Champions League semifinals.
A return to the Emirates beckons for the recently crowned French champions, who are facing an Arsenal side liberated by their success on the continent after watching Liverpool stroll to the Premier League title. This is a Gunners outfit intent on crossing new frontiers, but they're taking on a PSG that no longer boasts the tepidness which pervaded over their previous Emirates visit.
A blockbuster semi beckons, and here are four key battles which could decide the first leg on Tuesday night.
