Hurkacz rocketed down 23 aces including one clocked at 141mph -- the fastest serve of the tournament so far.
Djokovic will sleep a lot easier than he might have done if the 17th seed Hurkacz had taken the opening set after two aces saw him to 6-3 in the tiebreak.
Djokovic won both his points on serve to close the gap and then returned a Hurkacz howitzer and the Pole could only roll a forehand into the net.
This time Hurkacz's spinning volley crept over and Djokovic almost fell over the net as he missed the put-away.
Another tiebreak arrived and Hurkacz won a stunning baseline rally to save a set point but two points later he sent a forehand out to hand Djokovic a two-set lead.
Persons:
Serbia's Novak Djokovic, Poland's Hubert Hurkacz REUTERS, Dylan Martinez, Novak Djokovic, Hubert Hurkacz, Hurkacz, Djokovic, deuce, Andrey Rublev, Martyn Herman, Christian Radnedge
Organizations:
Lawn Tennis, Croquet Club, Dylan Martinez LONDON, Wimbledon, Djokovic, Thomson
Locations:
London, Britain, Russian