But the 26-year-old explains he was unable to play for Pompey due to them not being able to afford any appearance fee to be owed to his former club.
Mike Williamson: "They were dark times. But they are behind me now.
"Now it is a totally different contrast going to the Emirates.
"That's what makes all of those days when I was in the gym and staying fit worth it. It was hard. I was working on my own and trying to keep my head up, but this is the reward.
"It will be a big moment and a fantastic one to play at the Emirates.
"Every week it's something different. When it's at Old Trafford or the Emirates it does have that special feeling about it.
"But Arsene Wenger is a great manager and has his side playing great football.
"It's well documented how he pulls a player from nowhere and gets them playing. They come through the system and it certainly pays off when you look at the way they play.
"They will only get better.
"Beating Sunderland on Sunday was brilliant.
"Satisfying is the understatement of all time. Firstly it's three points, which we wanted to achieve.
"But more than anything we can take local pride out of it and a lot of confidence which we can take into our next game.
"We want to do well and produce some performances, but especially in a derby.
"Even living in London you can sense the rivalry between these two teams when you see it on TV. It's a special occasion. The atmosphere was amazing for us.
"The gaffer was right when he said we were disappointed to concede even one.
"But it doesn't take the gloss off a fantastic result."
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