AJAX :: Using Modal Pop Up And A Div With Two Buttons(yes,no) To Show Pop Up Windows?

I am using modal pop up and a div with two buttons(yes,no) to show pop up windows.In this scenario the user would select an item and click delete button.

Here the requirement is to show a pop up asking him "are you sure you want to delete?". IF he clicks Yes, the item should be deleted, If he clicks No, the item should not be deleted. To achieve this i have written a javascript function, which would be called on onclientclick event. in this function i am calls modalpopup.show(). In onclick event i have wired with server side event. But the server side event should be fired based on the selection the user made in modal pop up..But in my page, on the button click, client click fucntion is calling first and after executing this, it is automatically caling server side function. After that only the modal pop displaying..when i returned false from javascript funtion, server side func is not firing. I need the server side function to be called based on the selection user make in modal pop up..Is it possible?