Messias overturned his own decision to penalise Linvoy Primus for handling in the area when it was Anfield striker Milan Baros who was the offender, but he incurred the wrath of the Fratton Park faithful by awarding a second penalty after a perfectly-timed Matthew Taylor tackle on the Czech striker.
"A lot was going through my head after I saw Linvoy Primus jump up for the ball with Milan Baros in front of him," admitted Messias.
"One player's black and the other player's white, so I should have got it right straight away. But I think I blew too early and gave the penalty too quickly. As the Portsmouth players were complaining I kept replaying the incident in my mind.
"And after about five or 10 seconds I started to think I might have made a mistake and that Baros had handled it. I realised pretty early on I had got it wrong.
"I went over and spoke to my assistant referee, but he said he wasn't sure. But there was sufficient doubt in my mind to think I had made a mistake.
"So regardless of what people might have said, I thought it was best, in the spirit of the game, to get it right and change my decision."