Messi (29) and Neymar (25) are going through a great spell lately so, despite the strong lead, PSG defenders will have to be careful with the pair at the Camp Nou.
The Argentine is at present the Champions League's top goalscorer with 10 goals to his name, while Neymar has made more assists than any other player in the same competition, 7. They will both want to continue with their impressive stats as well as to aid their team to victory.
The couple's performances will no doubt be determining factors, alongside Luis Suarez's contributions, in attempting to pull off the miracle.