The 18-year-old was an imperious force on the right hand side of defence, showcasing incredible levels of composure and power for somebody making just their second Premier League start.
Speaking after the game, van Gaal pointed out how well the youngster performed and bemoaned his injury on 67 minutes.
“He did his job very well but he is injured and he has to go out and that’s a pity for the team,” van Gaal told MUTV.
The Dutchman went on to deny that Fosu-Mensah’s injury played a role in Man United’s collapse, which saw them surrender three goals in just six second half minutes.
“I cannot think that a consequence of Timothy’s injury is a 3-0 defeat, I don’t believe in that,” van Gaal added.
Van Gaal may not want to acknowledge it, but his over-reliance on youngsters this season has been blatant and somewhat staggering. There was a palpable difference in the back line’s entire shape after Fosu-Mensah limped off; suddenly everything felt less secure, less intractable. Spurs smelled blood.
Fosu-Mensah, against fierce opponents in a hostile atmosphere, was without doubt the most composed figure of United’s back four – despite being just 18. And while United’s current predicament is both tenuous and downright agonising, players such as Fosu-Mensah invoke hopes of a brighter future at Old Trafford.