Roger Federer and Novak Djokovic will meet in the semi-finals of Shanghai on Saturday (starting at 1pm UK time) for the fifth time this year and the 36th time in their career.  A win for Djokovic would see him level the H2H at 18 all.  Djokovic was first of the pair into the last four as he defeated David Ferrer in straight sets, 6-4 6-2.  It was a much easier match for him compared to the third round where he was pushed all the way by Mikhail Kukushkin.  Federer had that narrow escape in his first match against Leonardo Mayer, but has improved significantly in his next two matches, both straight set wins against Roberto Bautista Agut and Julien Benneteau.  In the quarters, Federer put on a great display to win, 7-6(4) 6-0.  The stats tell the story…