Ronald de Boer said Louis van Gaal will be privately unhappy with the football Manchester United are playing and said his former manager is "struggling" at Old Trafford.
Van Gaal claimed last week that United's players finally understand his philosophy and said his side's record was the best in the Premier League in recent months.
United then suffered only their second defeat in 20 games at Swansea on Saturday and while Van Gaal has said they are playing attacking, entertaining football, they have been criticised for being either ponderous in possession or direct.
De Boer played for Van Gaal at Ajax and Barcelona and during his first spell in charge of Netherlands and he feels the 63-year-old will not be happy with United's performances.
"Van Gaal is struggling a little bit at Manchester United," he told talkSPORT. "Not with the amount of points he's got, but with his style.
"It's not the way he wants to play. He's fighting to get there. At the moment it's not the football that we are used to with Louis."