Learn how to ride while looking backwards at your opponent (in sprints).
We had our club champs sprints round on Friday night. I've done a couple of exercises in riding while looking backwards, both through my legs and over my shoulder. I can't ride too straight while doing it yet, but it allowed me to watch my first round opponent (5 of us in grade so semi - best of 1) pulling up in behind me and opening up the gap to get a run at me. So while he was still making room, I gassed it and won by less than a foot. He has more top end than I do and I knew only tactics would beat him, and so I got to race the final and have my rear end handed to me to get second.
If you need to look forward to keep checking your line, then that is a perfect opportunity for the person behind to jump you.