Novak Djokovic remains on course for a record seventh Miami Open title, but the World No. 1 admitted to a loss of focus in a 7-5, 4-6, 6-1 victory over spirited Federico Delbonis which booked his place in the last 16.

Djokovic is hoping to eclipse Andre Agassi's six ATP crowns in South Florida over the next week and although he endured some shaky moments at Hard Rock Stadium, he still possessed enough quality during the key moments to see off the battling Delbonis.