Angry Djokovic regains calm to see off Shapovalov challenge

MELBOURNE, Jan 19 (Reuters) - Top seed Novak Djokovic regained his composure after a third-set meltdown to stave off the challenge of Canadian teenager Denis Shapovalov and reach the fourth round of the Australian Open with a 6-3 6-4 4-6 6-0 victory on Saturday.

The 14-time Grand Slam winner stamped his authority early on by breaking the 19-year-old's serve three times and converted his only breakpoint opportunity in the second set while leading 5-4 to take a 2-0 lead.

The 31-year-old lost his cool in the third set, however, after his request to turn off the artificial lights was ignored and he muttered to himself angrily and before losing two consecutive break of serves to concede the set.

The Serb let out his frustration with a huge roar when he broke Shapovalov early in the fourth, though, and romped through the rest of the set to remain on course for an unprecedented seventh title at Melbourne Park.

The reigning Wimbledon and U.S. Open champion will next meet Russian 15th seed Daniil Medvedev, who notched up his best Grand Slam showing till date by reaching the fourth round with a 6-2 7-6(3) 6-3 win over David Goffin of Belgium earlier in the day. (Reporting by Sudipto Ganguly; editing by Nick Mulvenney)