Sergio Garcia is off to a great start in the Castello Masters - leading by one stroke during the first round.

In danger of falling outside the world's top 10 - he was second at the start of the year - Garcia birdied five of his first eight holes to be one in front of fellow Spaniard Pablo Martin and Swede Michael Jonzon.

"I suppose being defending champion brings its own unique pressure," said Garcia, although he was actually speaking about the coming HSBC Champions tournament in Shanghai.

Paired with Jose Maria Olazabal and Darren Clarke, teammates from the 1999 and 2006 Ryder Cups, Garcia kicked off with back-to-back birdies and then picked up further strokes on the 14th, 16th and 17th.

Olazabal matched him on two of those, but Clarke bogeyed the 11th before returning to level par two holes later.

Martin, the first amateur ever to win on the European Tour, looked to have secured his card for next season last week, but a closing 77 in the Portugal Masters - he was playing alongside winner Lee Westwood - meant that at 111th on the money list he was still not safe.

Jonzon, another former Portuguese Open champion, had much more work to do, though. He was down at 158th and needed to climb into the top 115.

Colin Montgomerie was alongside Olazabal at two under, while German Martin Kaymer, playing his first event since breaking toes in a go-kart accident in August, was among the later starters.

By making birdie on the 18th as well Garcia turned in just 29 and by starting the front nine with another he was already seven under.

Jonzon was keeping pace with him at that stage, but a superb chip to within three feet on the long fourth took Garcia to eight under.

Montgomerie reached four under, but then drove into water on the third - as did his playing partners Robert Karlsson and Soren Hansen - and bogeyed.