$('#main_NestedMain_tbCity').autocomplete(
{ minLength: 1
, delay: 200
, source: function (request, response) { 
return ($.ajax({ method: 'POST'
                     , url: '/services.asmx/GetCities'
                     , contentType: 'application/json;charset=utf-8'
                     , data: JSON.stringify(
                            { prefixText: request.term
                             , count: 10
                             , country: $('#main_NestedMain_tbCountry').text() })
                    , dataType: 'json'
                   , success: function (data) { response(data.d); } })) } });