Midweek dismisssal of Liverpool the latest example of Messi's bravery and brilliance
I got to play against Lionel Messi just twice in my career. The first time was in a friendly at the Nou Camp, when Manchester City played Barcelona.
Messi only ca me on at half time - and he still won the Man of the Match award. We just could not get near him. As soon as you'd try to get close to him he'd put the ball through your legs or just knock it past you, he was impossible to mark.
Ten years on from that, we saw his greatness in the Champions League this week. And, for me, Messi is the best player of all time.
Even in the win over Liverpool on Wednesday night, Messi wasn't what you'd describe as amazing in the game overall, but he was there in the big moments when his team needed him and his two goals killed the tie off.
When you think about the best players in the world, you ask what makes them great. For me, it's winning big games for your team and he did that.
There was so much expectation, so much weight on Messi when he stood up to take that free kick, and he did it.
He's not the tallest player in the world, he has a low centre of gravity, but he is also very brave. He wants to get on the ball, he's not afraid of getting kicked. If you do try to kick him he will just come back for more, and that says a lot about him. He wants the ball, he wants to show what he can do. And that's what makes him so great.
When you are in the middle of your career you don't think too much about the chance to play against the truly top-class players. It's only when you retire that people ask you who was the best player you came up against.
I played for Ireland against Messi and Argentina in 2010. At the time you just want to go out and play, you think in your head you might be the one to stop him, to make a name for yourself.
I don't know who got to swap shirts with him after that game in Dublin, I'd imagine it was the captain so I didn't get to swap, but just being on the same field as him was enough compensation, instead of going begging for his shirt.
It's his consistency that marks him out as a true great. You have so many players who have a good season, a great moment, but for someone to do it consistently over 14 years, score 600 goals for his club, is something else. As an ex-player, it is a privilege to look back on my own career and say that I played against him.
But I can only think of what it would be like to play alongside him, to have Messi as a team-mate. You know that once he is in your side there is always a glimmer of hope.
I struggle to think of players I played against who have made such a big impact on their own. Sergio Aguero was a world-class player but he was a different type of player to Messi.
In terms of a player being like Messi, Eden Hazard has showed a bit of what Messi has. When Hazard is on his game he's unstoppable, that same low centre of gravity and you never know where he's going to take you, he just changes direction in a second. If Hazard had done it on a more consistent basis he would be further up there, but he just didn't have the same influence as Messi had.
As for the Champions League, that 3-0 win has the tie effectively won for Barcelona. You can't blame the Liverpool defence too much as Barca were just in that sort of form. Once they scored the second goal they looked like they wanted more. Liverpool lost all confidence, all the belief in what they were doing.
You can try and defend as hard as you can but when someone like Messi is capable of doing that from 35 yards out, there's really nothing you can do.
It's very hard to see Liverpool come back. Anfield is a special place on European nights and Liverpool will have that belief but we saw this week that if you give Messi just one opportunity, he will score. Barca have too much quality going forward to not score at Anfield.