The first leg will take place at Old Trafford, Manchester United must take advantage of opportunities when Barcelona travel to their headquarters, because when they travel to Camp Nou it will be difficult to develop a game.
If you count Head to Head in the Champions League, Barcelona is superior to Manchester United.
Both teams have the same chance to qualify for the next round, Barcelona is relying on a young squad this season, under Xavi's coaching many young players have developed so much, but in terms of experience maybe Manchester United is slightly superior.
In fact, the Manchester United vs Barcelona match will be very interesting to look forward to. Barcelona are the favourites, I think that's true because of the quality of the players at the moment. Manchester United have lost a player that other players respect, it was Ronaldo but it was an advantage for Barcelona. Xavi has to know what is needed in that game for them to qualify for the last 16, so I think Barcelona need to do something there then.
Both teams have an equal chance, but I believe that Barcelona's probability will be higher than Manchester United.