Andy Murray came through a tougher than expected first-round test against Zhang Zhizhen at the Shenzhen Open after the 21-year-old retired due to injury.

The latest stop on Murray's comeback from hip surgery should have been a comfortable straight-sets win after dominating the opener, but Zhang forced a decider before succumbing to the pain with the score at 6-3 6-7 (3-7) 4-2.

With less than 40 minutes on the board Murray was sitting with a one-set lead, however Zhang showed great determination to level things up – albeit after throwing away a 5-2 lead. Having lost the tie-break Murray started the third set well and just as he forged an opening his day was done, Zhang unable to continue when trailing by a break.

Murray will meet David Goffin next, the first time in two years the pair have gone head-to-head, with the three-time grand slam winner enjoying a 5-0 record over the Shenzhen top seed.

Speaking of the test posed by Goffin, Murray told a post-match media conference: "It's a really good test for me right now to play against guys that are in and around the top 10 in the world, I think he'll be highest ranked player I've played since I came back so it will be interesting to see where my game it at."

Denis Shapovalov is also through after dodging the rain to beat Ilya Ivashka, while Alex de Minaur needed less than an hour to dispatch Yuichi Sugita 6-3 6-0.

At the Chengdu Open, fifth seed Gael Monfils was a surprise first-round casualty as he allowed qualifier Lloyd Harris to come from a set down to secure his first win on the ATP Tour - the South African prevailing 3-6 6-2 6-1.

Fellow seed Tennys Sandgren also bowed out against Mikhail Kukushkin, but Matthew Ebden eased past Evgeny Donskoy in straight sets.

There were also wins for Sam Querrey and Taylor Fritz, while Ruben Bemelmans set up a meeting with Fabio Fognini after Mischa Zverev retired in the second set of their match.