Stephen Henderson slammed Pompey’s lack of fight and issued an apology to the travelling fans.
The Blues goalkeeper was picking the ball out of the net inside two minutes as Michael Kightly’s deflected strike found its way into the bottom corner and the Pompey preparations went up in smoke.
But Henderson felt the reaction to the early setback was not good enough from the team and did not mince his words.
Henderson said: ‘To all the fans who travelled up, on behalf of myself and all the players, we’d like to apologise because it was not an acceptable performance.
‘It’s an unbelievable following that came up.
‘In this day and age, it costs a lot to get up to Watford and pay for tickets so “thank you” goes to them and “please keep supporting us”.
‘It went wrong from the first minute.
‘But I don’t think we showed enough spirit to get back from when we let a goal in.’
‘It’s so frustrating because when you go a goal down, you want to see a bit more effort to get a goal.
‘We didn’t show it, that’s all I can say really.’
Henderson also confirmed Watford’s opener took a deflection as Michael Appleton’s reign as Pompey boss started with defeat.
The Blues keeper said: ‘I would be very disappointed if he had beaten me from there with a straight shot.
‘I don’t think it was even going on target and if it was, it was going straight at me.
‘But the deflection wrong-footed me.
‘We let the man cut inside and it’s unacceptable.
‘They had a few chances in the first half and we know we didn’t deserve anything from the game.’