Novak Djokovic’s third-round struggle with defending champion Grigor Dimitrov was halted by rain, forcing the pair to come back on Friday at the ATP-WTA Cincinnati Masters.

Officials called a halt to a frustrating day on which Roger Federer was never able to take the court for his third-round match against Leonardo Mayer.

Only two men’s quarter-finalists were decided as Milos Raonic defeated Denis Shapovalov 7-6 (8/6), 6-4 – avenging a loss to his young Canadian compatriot in Madrid three months ago.

Pablo Carreno Busta also advanced, beating Robin Haase of the Netherlands 6-4, 6-2.

Wimbledon champion Djokovic is vying to break through for a first Cincinnati win after coming up empty in five finals. He lost the first set 6-2 and won the second 6-3 when rain stopped the contest for 90 minutes.

When play resumed, Djokovic edged ahead 2-1 in the third, but another storm rolled in and organizers called a halt.

Cincinnati remains the only one of the nine Masters 1000 events that the Serb star hasn’t won. He has lifted trophies at least twice at each of the other eight events in the elite ATP series.

Bulgaria’s Dimitrov, who has won just one of eight prior encounters with Djokovic, prevailed easily in the opening set and broke early in the second before Djokovic roared back, breaking for a second time to take a 5-3 lead.

The 10th-seeded Serb squared the match as the day’s second bout of major rain moved in.

Earlier, Juan Martin del Potro at last managed to complete weather-delayed second-round victories. Argentina’s world number three del Potro had played just six points in the first game of his postponed second-round match against Chung Hyeon before the rain came again.

But the weather cleared long enough for del Potro to polish off a 6-2, 6-3 win over the South Korean to set up a meeting with Australian Nick Kyrgios for a place in the quarter-finals - a match originally set for Thursday night but now on tap for Friday.

Results

Men

2nd rd

Juan Martin del Potro (ARG x4) bt Chung Hyeon (KOR) 6-2, 6-3

3rd rd

Milos Raonic (CAN) bt Denis Shapovalov (CAN) 7-6 (8/6), 6-4

Pablo Carreño-Busta (ESP x13) bt Robin Haase (NED) 6-4, 6-2

With inputs from AFP