I would be betting my ace pre flop in a heads up game. So for that reason I'm assuming he doesn't have an ace due to his limp in. Normally I'm a mile out with these threads but I'm also not putting him on an open ended draw with KJ, as I'd be expecting him to raise pre flop with KJ. I'll plump for a spade flush draw but with him holding the Qs giving him (in his mind) a bit of a safety net as he will definitely not have you on an ace.
I'm 100 miles off aint i?
