Try to imagine only 7 minutes for Porto to equalize through the header of the two goals, it is not impossible not for Porto will continue to put pressure on Manchester United if the defense situation is weak, the goals can increase again.
As we know that Manchester United's performance is indeed bad from everything, especially the back line.
I saw a weakness that the Porto players exploited in the Manchester United defense, and that was the cross made from the right wing. 2 goals with the same scheme and it's clearly bad.
I've already said that Porto are very unlikely to be underestimated and they will try their best to come back and avoid defeat. Playing at times clearly made them more confident, but Manchester United should have reacted better in the second half. Ten Hag needs to evaluate his defensive weaknesses today and he needs to improve them in the second half.
The second half will be the final decider for Manchester United because for me Porto is clearly confident at home while the visitors they have to evaluate again and as I know Erik Ten Hag's evaluation is sometimes not so effective.