The North London outfit suffered an embarrassing 5-1 defeat to relegated side Newcastle away from home in the Premier League on Sunday afternoon.
Spurs needed just a draw against the Magpies at St. James’ Park to finish second, but they suffered a stunning collapse.
What was most shocking was that Newcastle actually ended the game with 10 men due to the sending-off of Aleksandar Mitrovic in the second half.
Pochettino has criticised his players for their performance against Rafael Benitez’s side, and has claimed that they appeared to be on holiday.
"We had the possibility to stay second and how we lost and how we gave to the opponent that is relegated, in the first and second half, they score three goals with 10 players it is the worst day as a manager and I feel very disappointed,” the Argentine boss told BBC Sport (17:22).
“We need to be sure that never happens again and need to improve our mentality. We were on holiday and that is the reality.”
Tottenham were in the running for the Premier League title just a few weeks ago, and the way they have played in recent matches has been disappointing.
The North London outfit should have come second, but they have ended up third behind an Arsenal side who were not even in the title challenge for the past several weeks.