IIRC, Button was comfortably in the lead in the wet but was overtaken by Schumi as the tracked dried and then his engine blew
IIRC Button may still have been in the lead before blow-up, but yes, Schumacher would have passed him sooner or later. Nonetheless his career first podium was clearly on the cards and I remember Button giving an interview after a race, how he couldn't believe to be so unlucky never to achieve a podium in F1. Well, that luck has changed quite a bit by now 6 years later.