The 63-year-old Dutchman has been criticised after unconvincing start to his Old Trafford reign despite guiding the Red Devils into the top four.
There is no question about the philosophies he has put in place at Ajax or Barcelona or his achievements
Liverpool can hoist themselves above Van Gaal’s side and into fourth place if the Reds beat their bitter rivals at Anfield in the Premier League on Sunday.
However, Rodgers is a big admirer of the former Barcelona and Bayern Munich manager, adding that Van Gaal will finish his United reign with his reptutation intact.
“I don’t think there is any convincing (required). He has shown over his career that he is a top-class manager,” Rodgers is quoted as saying during his pre-match media conference on Friday.
“He will have seen, coming into this country for the first time, the challenges of this football – it is why it is the most competitive league in the world.
“The Premier League is different from the leagues he will have worked in before but I don’t think you can argue with his credentials.
“There is no question about the philosophies he has put in place at Ajax or Barcelona or his achievements and when he leaves Manchester United he will still be one of the great managers.”
Liverpool kept pace with their top-four chasing rivals thanks to a 1-0 win at Swansea City on Monday night.
The Reds can hoist themselves above the 20-time English champions with victory on Merseyside on Sunday afternoon.
United still have to face local rivals Manchester City, leaders Chelsea, Everton and Arsenal before the end of Van Gaal’s first season in charge at Old Trafford.
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