#2 Momentum and form
Two months ago one wouldn't have expected that Manchester United would go into the tie with greater momentum than PSG.
The French team topped their tough Champions League group and were unbeaten in the league for a very long time. Manchester United, on the other hand, lost to Juventus and Valencia in the Champions League and were struggling at the 6th position in the Premier league.
Since the time Ole Gunnar Solskjaer has arrived at the club though, United have won 8 out of the 9 matches and are still unbeaten. The Red Devils have won the most points, scored the most goals, conceded the least and have hit more shots in the league since the time Ole took over.
PSG, on the other hand, have lost 2 out of the last 6 matches they have played. PSG recently got beaten and dominated by third-placed Lyon in the league.
They say momentum and form play a huge role in football, and currently Manchester United have more momentum than PSG going into the clash. While anything can happen on a given day, good momentum will provide United an edge over their French rivals.