Novak returned to The Boodles tournament, the traditional Wimbledon warm-up event at Stoke Park in Buckinghamshire, to finalise preparations for the defence of his Championships title.
Djokovic clinched his first win on grass this year beating world no.35, Chilean Cristian Garin, 6-2, 6-4 on Tuesday.
Nole made a confident start, breaking his rival twice for a 4-0 advantage, and went on to take the first set.
Garin broke first in the second set to clinch a 4-2 lead, but the Serbian star responded strong by winning the next four games.
The world no.1 will play his second match on grass on Wednesday at 15:30 CET, when he faces Canadian Denis Shapovalov.
Photo: Kevin Palmer/The Irish Independent