One more win will take Djokovic level with John McEnore's record start to a year from 1984, and within three victories of the best-ever winning streak in tennis, set by Guillermo Vilas in 1977 at 46.
Wawrinka, 25, comfortably defeated the former Grand Slam winner 3-6 4-6 4-6 with a superb performance, playing excellent tennis, to set up a last-eight clash with Federer.