(Photo credit: Geoff Burke-Imagn Images)

Novak Djokovic opened his quest for a record-extending fifth Rolex Shanghai Masters title Friday with a hard-fought 7-6 (2), 6-4 win against Marin Cilic.

With the victory in one hour and 55 minutes, the fourth-seeded Serbian improved his career record to 40-6 at the ATP Masters 1000 tournament in China. He also improved to 20-2 against Croatia's Cilic.

Djokovic fired 10 aces, saved all four break points and finished with 21 winners and only four unforced errors. He converted the only service break of the match in the third game of the second set.

With their combined ages of 79 years and 139 days, the duel between Djokovic and Cilic marked the oldest men's main-draw meeting at the ATP Masters 1000 level since 1990.

'Tons of respect for Marin, all he has achieved and who he is as a person,' Djokovic said. 'We get along very well off the court, we've known each other for many years. The last time we played was three years ago, so it's great to see him back playing at this level.'

Djokovic became the first man to record 40 or more wins at six different ATP Masters 1000 events since the format was introduced in 1990: Rome (68), Indian Wells (51), Paris (50), Miami (49), Cincinnati (45) and Shanghai (40).

The 24-time Grand Slam winner's third-round opponent will be German qualifier Yannick Hanfmann, who upended No. 25 seed Frances Tiafoe 6-7 (9), 6-2, 6-1 in two hours and 51 minutes.

Tiafoe wasn't the only seeded player shown the door in the second round. Belgium's David Goffin dumped No. 6 seed Ben Shelton 6-2, 6-4 and countryman Zizou Bergs beat No. 11 Casper Ruud of Norway 3-6, 7-5, 4-1. Monaco's Valentin Vacherot eliminated No. 14 Alexander Bublik of Kazakhstan 3-6, 6-3, 6-4. Spain's Jaume Munar took out No. 22 Flavio Cobolli of Italy 7-5, 6-1.

Shelton was playing for the first time since sustaining a left shoulder injury at the U.S. Open in August.

No. 5 Taylor Fritz rallied for a 2-6, 7-6 (4), 7-6 (1) win against Hungary's Fabian Marozsan and No. 10 Holger Rune of Denmark was a 7-5, 6-4 winner over Argentina's Sebastian Baez.

Other seeds safely through to the third round were No. 19 Francisco Cerundolo of Argentina, No. 20 Tomas Machac of the Czech Republic, No. 21 Ugo Humbert of France, No. 27 Tallon Griekspoor of the Netherlands, No. 31 Gabriel Diallo of Canada and No. 32 Giovanni Mpetshi Perricard of France.

--Field Level Media