Avoid to mix those two up. Do NOT nest them to trigger rerendering, like this:
<a4j:commandLink ajaxSingle="true" actionListener="#{...}"> <a4j:support event="onclick" reRender="..." /> </a4j:commandLink>
It will lead to funky behaviour, sometimes sending the link, sometimes not. If you use a4j:commandLink you do not need a4j:support. Do trigger rerendering from within the commandLink.
<a4j:commandLink ajaxSingle="true" actionListener="#{...}" reRender="..." />
Tags: jsf, rich faces