Not only Federer loses very sparingly - when he does, it is often against younger players. Before today, the last time he lost against someone older than him was the AO 2005 SF - over two years ago
Until 2004, he lost against much older players often - think Henman or Costa. However, as he matured himself he became almost invulnerable against players born after him. Even Marat isn't that much older than Fed, especially compared with Cañas.
Another little fact that makes Cañas win even more one-of-a-kind.