Thursday 28 July 2016 14:55, UK
Novak Djokovic was given a stern test at the Rogers Cup in Toronto where he survived two tight sets to beat Luxembourg's Gilles Muller.
Playing his first match since losing in the third round at Wimbledon, the world No 1 was on court for 104 minutes in posting a 7-5 7-6 (7-3) victory.
Djokovic needed two chances to wrap up the win, after he failed to serve out for the match in the 10th game of the second set, when he was broken to 15.
However, he recovered his composure in the tie-break which he took 7-3.
Muller, the 33-year-old world No 37, appeared to be staging a recovery towards the end of the second set but - from 3-1 up in the tie-break - he was powerless to prevent the Serbian from reeling off six straight points.
Djokovic, who suffered a shock defeat at SW19 earlier this month when he lost to Sam Querrey, will now face the experienced Radek Stepanek in the last 16.
"It's tough playing the first hardcourt match since March. It was hot and that made the ball move very fast," Djokovic said. "It was hard to control, it was not easy to play. But I managed to stay tough.
"I was disappointed to lose serve twice in the second set when I was up a break but I was just glad to close this out in straight sets."
It was his 18th victory in his last 21 matches in the tournament which alternates between Toronto and Montreal each year.
He reached the final 12 months ago losing to Andy Murray who is not defending his title this week, as the Scot is taking an extended break following Wimbledon ahead of his Olympic Games defence.
Meanwhile, home favourite Milos Raonic beat Yen-Hsun Lu 6-3 6-3 in his first match since losing to Andy Murray in the Wimbledon final, and No 3 seed Kei Nishikori was also tested in his 6-4 7-5 triumph over American Dennis Novikov.
The match contained eight breaks of serve, with Nishikori going through to face another American - Rajeev Ram - in the last 16.
Ivo Karlovic continued his excellent run of form by seeing off the former US Open champion Marin Cilic.
The 37-year-old won the battle of the Croats 6-4 7-6 (7-3), with the No 8 seed unable to cope with his compatriot's huge power.
The big-serving Karlovic fired down 20 aces - to just three by his opponent - and not surprisingly banked 84% of his first serve points.
Since Wimbledon, his win-loss record is an impressive 10-1, a run that brought him the title at Newport, Rhode Island, along with a final defeat in Washington DC last Sunday.
Elsewhere, Sam Querrey - who conquered Djokovic at Wimbledon - was forced to retire in the second set as he lost to David Goffin. The American was 6-4 2-1 down when he chucked in the towel, while Ryan Harrison beat compatriot John Isner in three sets 7-6 6-7 6-4.
There were also wins for Rajeev Ram over Lucas Pouille, Radek Stepanek against Peter Polansky, Bernard Tomic over Steven Diez and Jack Sock against Donald Young, while French Open semi-finalist Dominic Thiem retired in the first set against Kevin Anderson, Fabio Fognini lost in three sets against Jared Donaldson and Gael Monfils beat Vasek Pospisil.
