After a clutch of shanked backhands, Federer started running round that wing which opened up more angles for Nadal which he exploited to snatch the opener in 58 minutes.
Nadal was swinging his two-handed backhand like an axeman felling a giant redwood and Federer was on the back foot.
Always dangerous when he is down he punched back from being broken in the fifth game of the second set and broke twice himself to seal it 6-3 and level the match.
At that stage, Nadal's semi-final -- the longest in the tournament's history at five hours 14 minutes long -- looked to be weighing heavy on him but he dug deep.
The shots he chased down elicited more screams and squeals from the packed crowd than a fairground ghost train and the crowd was a sea of red and white, and red and yellow, incredulous faces.
Stinging Groundstrokes
As gulls whirled overhead, their white underbodies lit bright by the floodlights, the Spanish left-hander went after Federer.