About 18 months ago I went to play in a competition in Vienna. I played Bach's prelude and fugue in D from WTC-2, Moskowski 1st Etude and Haydn E-flat major sonata No.49. All pieces I could play perfectly at home. All pieces were well within my technical range. So, I went on the platform and performed.
The Bach went so well, I don't think I've ever played that well before or since. It was without a doubt one of the most beautiful performances that you're ever likely to hear, even if I say so myself. Trouble is I couldn't bottle up the thing that made it beautiful and sell it, because if I could, the next thing might not have happened
The Moskowski. I totally screwed it. I got through it but it was splashy, choppy, lumpy, tense, harsh, I mean, it was rhythmic at least ( I ALWAYS play in time, luckily, although not always well!!!!). With the first mistake I tensed and it led on to a horrendous experience on the platform. After which I had to play the Haydn, which was somewhat luke warm because of what happened, and I had a huge memory slip thinking about the Etude whilst performing the Haydn.
I guess the thing is that I have an excellent technique. I know how to use my body and hands at the keyboard to get the sounds I need for the repertoire I play. I know this because I wouldn't be able to play so well in the practice room. However, at that point it wasn't secure enough to take on the pressure of a competition. When you get nervous, the first thing to go is finger strength (ok I know its a BAD term, finger strength but you all know what I mean). Then, the ability or desire to listen goes, and then things go base over apex.
I am constantly working on my technique to repair holes in it, I mean, as well as working patiently on repertoire and focusing on the music. What I'm getting at though, is that if you have any weak points in your technique, even if they are normally under control, they will come to the front in a performing situation.
Incidentally after the performance I went out to the pub with my best friend, had a laugh about it, had a drink and enjoyed the rest of the week in Vienna. It was only one competition.
The ONLY thing I kick myself about is that the adjudicators came up to me and said 'When you played the Bach, we thought we had the winner'..... oh well, not on that day!