In Saturday's semifinal matches Raonic outlasted fellow Elite Eight member Tomas Berdych in three sets while Djokovic got revenge on a clearly exhausted 2014 US Open finalist Kei Nishikori by dispatching the Japanese player in just over an hour 6-2 6-3. (Nishikori had just sealed his own qualification for the ATP World Tour Finals in London by outlasting David Ferrer in 3 grinding sets.)
On Sunday, Raonic will face Djokovic for the fourth time having never beaten him (although this time is their first meeting in a final and first time not on clay) and hope that he will be able to achieve some more firsts: first time win of an ATP Masters shield and a first win over Djokovic and a World #1.
Somehow I think that will be a bit too high hurdle for the Canadian to climb. Djokovic is on a 26-match winning streak on indoor hard-courts. The last person to beat him on this surface was Sam Querrey (at the 2012 Paris Masters). if Djokovic does win on Sunday then he will only need to win one match in London to maintain his grip on the #1 ranking. Even if he loses to Raonic, he would retain the World #1 by getting out of the round-robin section of the year-ending championship, so the likelihood of Federer ending the year ranked #1 for a 6th time is looking very small.
MadProfessah's pick: Djokovic.