Novak Djokovic believes that Ryan Harrison will come back stronger from his crushing loss to the world number one.

Djokovic dropped just six games on his way to victory, striking the ball well and rarely giving his 20-year-old opponent a chance.

The defending champion also said that it was tougher for the young guys coming through because of the constant improvement among the top four players.

"I tried to focus at the start," said Djokovic. "I knew he had nothing to lose and would come in serving big, which he did.

"It is unlucky for Ryan that he maybe didn't play his best today, but he will be back and will be stronger for sure.

"[It is tougher for guys coming through] because nowadays players are so committed and so professional, especially the guys at the top. We are constantly pushing each other and making each other stronger."

Djokovic will play Radek Stepanek in round three.