The former Red Devils skipper came up against his former side as the 20-time English champions were 5-3 winners on penalties against Inter Milan following a goalless draw on Tuesday.
They are happy with what they are doing and for that reason it will not be difficult for them this year
Vidic, who moved to the Serie A outfit at the end of the season, is expecting the Red Devils to have a good season under the 62-year-old Dutch coach after a seventh-place finish last term.
“Van Gaal has a lot of experience, he has trained a lot of teams in a lot of leagues and that shows he knows what he is doing,” said Vidic.
“I believe he can do good work and the players think the same.
“I was in the dressing room with the players after the game and they were all positive and happy with everything that is happening at the moment.
“That is a good sign. I am pleased to see that.
“They are happy with what they are doing and for that reason it will not be difficult for them this year.”
Vidic won five Premier League titles, the Champions League and League Cup during a decorated career at Old Trafford.
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