Sergio Garcia got off to a quick start in his bid for a third consecutive Valderrama Masters title on Thursday, as a three-under-par 68 left him just two strokes off the early clubhouse lead.
Half of the field will finish their opening rounds on Friday after lengthy delays due to thunderstorms in Andalusia.
England's Ashley Chesters claimed the clubhouse advantage with back-to-back birdies closing out a five-under 66, with Frenchman Gregory Bourdy, who may need to win this week to keep his European Tour card, one shot behind.
The tournament host Garcia has won six of his 14 European Tour titles in his home country, including this event in the last two editions in 2011 and 2017.
The 38-year-old was four-under through 11 holes before his lone bogey of the day, but was delighted with his opening effort.
"Any time you shoot under par on this course -- it doesn't matter about the conditions -- you're happy. So I'm obviously happy about it," he told europeantour.com.
"I saw a lot of great things and a couple of things that we need to improve but overall it was a good day."
The world number 31 has had a difficult season, although was impressive as a wildcard in Europe's Ryder Cup victory last month, but is favourite to win in Spain and is ranked 56 places higher than anyone else in the field.