Van Gaal and Giggs did not enjoy the best of spells in the Manchester United dugout and with the former having departed Old Trafford, even the latter is expected to leave within the next few days.
Not many were impressed with the work van Gaal and Giggs have conducted at United over the last two seasons but Fosu-Mensah remains grateful to the duo and has revealed that he has learnt a lot under their tutelage, as well as gaining a handy education from the club's more experienced players.
Fosu-Mensah told Voetbal International: "I can only speak for myself and, for me, Van Gaal was good, the best I ever had.
"Yes, he was present and he talked a lot, but he was like that with everyone, with the aim of improving you as a player. He succeeded in doing that with me. I can notice that about everything.
"Ryan Giggs talked to me a lot. For example, after the semi-final of the FA Cup against Everton, when I played well, but also caused a penalty. 'Stay on your feet in such a situation,' Giggs said. I learned so much from that.
"I listen to Michael Carrick, Chris Smalling and to the Dutch guys, Daley Blind and Memphis Depay. I sit in the dressing room and just listen to what everyone has got to say, and especially to our captain, Wayne Rooney."