i assume both of you have 2000 chips. Then no i wouldn't go all in with 33 or A2. If the players is tight/good he probably has you crushed.
However in Heads up sng's i play the players more then i play the cards. If the players is tight i will steal and push more. If he's loose and bets alot, tries to steal alot. Then i will try to trap him, or catch him on a bluff and reraise it with air myself. So it really depends on what type of player your playing against.
But personally if the stacks are about equal, and you still have plenty BB's i won't push or call with 33. It's a coinflip at best, and i came to play poker. Not to win by getting lucky. I don't see a reason to do coinflips unless you have 75% of the chips or 25% (are behind alot or are far ahead).
I suggest just using it as a guideline instead of something you should always do. Personally i just trust my instinct, use my experience i've gotten so far, the cards and my reads on that person. I apply the strategies i've read on this site, but it's never good to follow hand charts blindly if you ask me.