Novak Djokovic overcame Denis Shapovalov to book a Shanghai Masters last-16 spot as he made an impressive start to his defence of the title.

The Serbian wrapped up a 6-3 6-3 victory as he bids for a fifth trophy success at the event, where he will face John Isner next.

Isner, seeded 16th, beat Lucas Pouille 7-5 6-3, while Dominic Thiem also progressed to the next round courtesy of a 7-6 (7-3) 6-3 victory over Pablo Carreno Busta.

That was the final match on court and rounded off a day in which all 10 clashes were decided in two sets.

DOMINANT DJOKOVIC SOUNDS WARNING TO RIVALS

Shapovalov played well but could not keep pace with his illustrious rival across the net, Djokovic dropping only one point on serve in the first set.

No man has won more titles at this event than Djokovic and, on this evidence, he will be adding to his tally.

Djokovic was deadly accurate and coasted through his service games, dictating rallies and offering almost no hope to his Canadian opponent.

Even when Shapovalov upped his game on serve, Djokovic produced a string of superb returns to maintain the ascendancy.

In the other half of the draw, fourth seed Thiem battled past Carreno Busta as the Austrian advanced his claims for a second Masters win of 2019, having won at Indian Wells. 

The Austrian saved three set points in the opener and took control of the tie-break before settling matters in a more comfortable second set. 

TSITSIPAS, ZVEREV AVOID TIE-BREAK TROUBLE

A straight-sets win may always seem simple on paper, but Stefanos Tsitsipas and Alexander Zverev were both made to work hard for their victories.

The pair were each taken to consecutive tie-breaks, the Greek defeating Felix Auger-Aliassime 7-6 (7-3) 7-6 (7-3), while Zverev was pushed further still in a 7-6 (15-13) 7-6 (7-3) success against Jeremy Chardy.

Sixth seed Tsitsipas, who has won in Estoril and Marseille this year, will be favourite to overcome Hubert Hurkacz for a spot in the quarter-finals.

Zverev, seeded one place higher than Tsitsipas, faces Andrey Rublev as the German goes in search of a fourth Masters title.

SEEDS SAIL THROUGH 

Four other seeded players enjoyed straight-sets wins, with Karen Khachanov, Roberto Bautista Agut, Matteo Berrettini and David Goffin securing their progress.

Khachanov beat Taylor Fritz 6-2 6-4, Bautista Agut – runner up in 2016 – defeated Reilly Opelka 6-4 7-5 and Berrettini was a 6-3 6-3 winner over Christian Garin.

Goffin was 6-2 3-0 up against Mikhail Kukushkin when the Kazakhstani retired hurt.