Unless you've switched frequency the plane in the circuit will have heard you call for joining instructions and that you were told to report downwind, so he should have a pretty good idea of your whereabouts.
If you joined the frequency after that planes last call you might not be aware of his position, but there's a pretty good chance you would have heard him being cleared for a touch-and-go and know he's in potential conflict with you. So hopefully it's not quite a s bad as you make out.
And I think unless you are flying IFR or have a radar service then it's 'see and avoid' even if you are talking to an ATC unit with radar.