Australian Cameron Smith's blemish-free eight-under-par 64 catapulted him to the top of the leaderboard after the opening round of the CIMB Classic in Kuala Lumpur.

Smith, who broke his duck on the PGA Tour in May at the Zurich Classic of New Orleans alongside Jonas Blixt, made birdies at the third, fourth and fifth and picked up further shots at the seventh and ninth to approach the turn in 31.

A fine approach shot on the 14th left a short putt for another gain and he closed his round with back-to-back birdies to hold a one-shot lead at the end of a first day that was played in stifling conditions.

He said: "I grew up in Brisbane. It's kind of similar to this but obviously not as bad as this. But yeah, I enjoy the heat. I always play well in the heat for some reason, I honestly can't tell you why.

"I have to keep the game-plan pretty much the same really: just be smart off the tee, try to hit the fairways and then really aggressive into the greens. It worked so I'll keep that one."

Poom Saksansin and American pair Xander Schauffele and Keegan Bradley are breathing down Smith's neck in the event, which is the first of three on the PGA Tour to be held in Asia in successive weeks.

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Thailand's Poom, who made six of his seven birdies on the front nine, said: "I played without any expectations. I just kept playing and the ball kept going in. This is a big event but there is no cut so I'm only feeling 50 per cent pressure."

US PGA champion Justin Thomas has won the event for the past two years and started the defence of his title with an opening 70 that featured five birdies and three bogeys.