Alex Mowatt believes Nathan Thompson ‘bought’ his sending off in Oxford United’s 3-0 loss at Pompey.
And the U’s midfielder insists his side would have grabbed at least a point if he’d have stayed on the pitch.
Mowatt was dismissed in the 62nd minute for violent conduct at Fratton Park on Sunday.
He took a left-handed swipe at Thompson, after the Blues man appeared to goad the Barnsley loanee for missing a penalty.
Mowatt revealed he was already frustrated with himself for striking his spot-kick against the post.
Thompson’s actions sparked a reaction from the 23-year-old – although he knows he shouldn’t have raised his hand.
Mowatt told the Oxford Mail: ‘That is probably the worst 60 seconds I’ve had in football.
‘I’ve missed a penalty so I’m already angry with myself.
‘Then he’s got in my face and I have reacted stupidly.
‘I don’t think you can come in someone’s face like that after they have just missed a penalty.
‘He’s bought it really, I’ve only pushed him but you can’t raise your hands.’
Mowatt had the chance to draw Oxford level from the penalty spot – but his effort crashed against the inside of the left-hand post.
Kal Naismith had given Pompey the lead on five minutes, converting from close range after Matt Clarke headed Dion Donohue’s corner back across goal.
The U’s, under new boss Karl Robinson for the first time, were on top before Mowatt was sent for an early bath.
James Henry cracked the bar in the 21st minute.
Luke McGee also tipped Malachi Napa’s 25-yard drive around the post, while Brett Pitman also cleared off the line for the Blues.
The hosts took full advantage of Oxford going down to 10 men.
Pitman fired in a double for a second successive week as Pompey ran out 3-0 winners and moved to within two points of the play-off places.
However, Mowatt is adamant Oxford were the superior outfit.
And he took full responsibility as he felt his actions cost his side at least draw.
‘I thought we were the better side,’ the former Leeds player added.
‘I take full responsibility, I think I cost the boys.
‘The least we go away with is a draw if I stay on the pitch, even if I miss the penalty.’