If your enemy plays good certainly he dont have a nines, but like you told in start of tournament he is play like donkey and have a lucky raises with K 8s for example. 8.5k is more than 1/3 of your stack (23k), then if you go you have to all in, or just fold to protect your stack to play better hand and flop. I would all in. I think he s have a AJo or ATo, because he dont re-raised in pr? flop and i think hes go with ases in hand with another top card.