Barca playing at home first it quite a good advantage for them. Barca performance is unique and they are topping their league,they have mostly won MU in their home. Lewandonski is a wonderful striker which makes might break into MU defence.
MU has been in good form and the qualities of the players are increasing day and the team has a good defence,which makes this match unpredictable yet until on the match day,when these two clubs will be on the field playing.
The quality of the two players has a balance, which means that the match will be fierce and difficult to predict, it's just that Barcelona has the advantage of playing at home in the first round, not only Lewandonski Barcelona also has the strength of young players who can trouble Manchester United's defense, but the biggest role what can distinguish only the strategy that will be implemented by the coach when the two will meet at Camp Nou, I think the strategy implemented by the coach is the key to victory.
Manchester United also have Casimero who knows Barcelona's playing style by heart and they also have Marcus Rashford whose performance is getting sharper up front, Erik Ten Hak can take advantage of the strengths they currently have, at least being able to hold Barcelona to a draw, so that Manchester United can play openly and take chance to beat Barcelona at Old Trafford in the second leg.