During the epic 1989 Ironwars battle in Hawaii, it was Dave Scott who commanded the lead, and Mark Allen who followed...at least until there was 2.4 miles remaining in the race.
Dave commented he didn't mind Mark tagging his shadow all day long. Disclaimer here: Dave stated that Mark was racing clean and held a legal draft distance throughout the 112 mile bike segment. In the run Allen was tucked in alongside the entire way, letting Scott set the pace.
After 25 years of endurance sports racing, I'd suggest it's best to get the dude off your tailpipe. Racing is a mind game and I don't like showing my hand of cards while someone watches.
This brings up the subject of passing. I'd suggest it's best to lay back, get calm, and then lay down a decisive move that lets your opponent know it's not tiddlywinks on this day. Here are a couple of master competitor moves you can try at home:
1) Get your breathing controlled and quiet. You don't want to be wheezing and gasping as you charge by. Instead make it the stealth mode and convince the competitor you're barely working.
2) Keep your body erect and your gaze far off into the horizon. NEVER look at an opponent when passing...you must project the image of aloofness, as if it's just another pass among a thousand others you have made that day. Make eye contact and you might bring out the tiger in the other guy, which means you're in for a painful, unproductive throw-down battle.
3) If you're cycling, perform the above two points and add a third: Right at the time of the pass, upshift a gear and power away. There's nothing like the "click-ching" sound of a Shimano shifter grabbing a gear. Perform the above passing techniques in the proper sequence and you'll demoralize the field around you.
The overall idea is to let the athlete next to you think your still have a full tank of gas, so that he/she doesn't answer the call and race you. You want the pass clean, and you want it to stick.
So as Mark Allen would state "peaceful yet strong." Bring it to the competition hard and fast, bring it from behind, and make sure you keep the rats from biting your tail.