The defense of Manchester United operated badly before the international days and their injuries and absence will make the defense weaker.
What opponent will they face in the weekend? Leicester City that are never a weak team in Premier League in the past 5 years. In the past two seasons, sometimes they joined the title competition. It is enough to say about their strength and Manchester United will face with a very dangerous opponent.
Vardy will be one of hope for Leicester City. He is good and not appear in a
list of suspended or injured playersNo matter how "bad" Leicester seems at any point, they are always doing fine compared to what people are expecting of them, they were a team that literally dropped to championship and failed to promoted and then became a team that won the league and ever since that day they have finished in the top half of the league as well.
This doesn't mean that anyone expects them to win the league, which would be another shock if it were to happen again, but at least people are not giving 1/5000 odds for them anymore. United is a lot better team, and they will probably beat Leicester easily, but that doesn't mean that Leicester has zero chance, that team has a chance against everyone, not because they are just good, but because they may take it up a gear and suddenly play better than expected in some games.