Harry Redknapp cancelled Christmas for his players after the 3-0 defeat at Southampton.
Pompey were left stuck in the bottom three and facing a new year relegation fight after losing at St Mary's.
Redknapp told his beleaguered charges: "We're going to train every day including on Christmas Day."
The Pompey boss added: "We play on Boxing Day and I'm going to be the most miserable person you've ever seen in your whole life."
Redknapp was particularly frustrated with substitute Boris Zivkovic, who was caught napping as Marian Pahars scored Southampton's crucial second goal.
The manager said: "I put a sub on and the first thing he did was let Pahars
come inside on his right foot for their second goal.
"Afterwards I said to him 'Did you watch the first half? Were you busy doing
something else?' He must have been asleep."
Redknapp added: "I don't know how we were 1-0 down at half-time because they were rubbish and
so were we.
"Their first goal was direct from a corner and that was a terrible goal. I
need to put some springs in the goalie's boots.
"If you don't concede silly goals, you don't get beat."