When did Federer really believe he could 'hurt Nadal' on clay?

Ivan Ljubicic is the former coach of Roger Federer. LJubica won three Grand Slams with Federe. He also won the Australian Open in 2017. Feder retired in 2016. L Jubico talks about his coaching career on the Tennis Podcast. The interview is recorded by David Law. It is a good timing as Federen plays in the Laver Cup. In the interview L jubics talks to Law about their coaching partnership. They discuss their training methods and their success. After the break, they trained during the long break before the 2017 Australian open.