Darren Clarke made an excellent start before missing out on the opportunity to assert his title claims on the first day of the Portuguese Open.

Clarke raced to six under after nine holes at Oitavos Dunes, but three bogeys thwarted his progress to finish on three-under 68.

Gonzalo Fernandez-Castano took full advantage of Clarke's stumble, equalling the course record of 64 with eight birdies and a solitary bogey.

The Spaniard leads South Africa's James Kamte by one stroke.

The British trio of Barry Lane, Simon Dyson and Steve Webster share third place after rounds of 67.

Fernandez-Castano matched the course record jointly held by Simon Dyson and Jamie Donaldson.

"Hopefully this will be a confidence-booster this week and I can play well when the big points can be earned," said Fernando-Castano, 27, who is aiming to boost his Ryder Cup hopes.

Clarke's superb front nine saw him register a lead of three strokes at the turn.

But his indifferent putting on his back nine saw the Northern Irishman lose ground.

Clarke has shown glimpses of a return to form this season.

Third in the South African Open before Christmas and fourth in the Joburg Open in January, he also had a 10th place finish in Malaysia last month.

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