AZT, For me, in competitive situations, mental focus and hormones trump what one was able to do in training. Last year, I did a stage race that featured a TT and circuit race on Saturday and a 70 road race with wind and some climbs and very rough road on Sunday. On lap one of the road race, I was with the lead pack and everything was possible. I was hitting power numbers that normally would have been a problem. On lap two, we did a short steep climb that was one of those 600 watt affairs and I was toward the back because we had led up to the climb on a straight section of road with the wind at our back so the field strung out.
Once to the top there was a downhill section that we were told specifically to take it easy due to gravel and rough road. I lost a little focus and as I finished the downhill the front of the field accelerated, strung out, went to the gutter in a strong cross wind. I got gapped and it was impossible to close. I made the mistake of using all I had to catch them resulting in pulling a couple of guys behind me who could then pass me and go on. I was all alone and then NOTHING was possible. 150 watts seemed like an effort.
Free you mind from the limits of training. Trust your fitness. You will have a lot more in the tank than you think. You are as good as these guys! Monitor your breathing and if you get gaspy, then it is time to think about backing off.
If you get gapped, do not do what I did. Know you are gapped and take stock of your resources. Who is behind you? Do not try to give chase unless you are absolutely know you can catch them.
Having said all that, it is also a good idea to negatively split a long timed event and try to find a group to ride with that will task you without blowing you up on the first 1/3 or the race.
Good luck and have a great race.