Safari 5 bug - Radio button's checked="checked" attribute is ignored when loaded via AJAX

Strange bug with Safari happening when a radio button input is loaded via AJAX. The relavent code is

<input type="radio" name="team" value="231" style="width:auto;"开发者_运维知识库 checked="checked"/>Team 1

<input type="radio" name="team" value="232" style="width:auto;"/>Team 2

When this code is loaded with plain old html, the first radio button is checked as it should be. But if the same exact code is loaded via ajax, Safari doesn't actually show any indication it is checked, even though the checked="checked" attribute is there in the source.