Frenchman Julien Guerrier opened up a one-shot lead after the opening day of the Andalucia Masters as world number one Jon Rahm equalled his worst ever round at a European Tour event.
Guerrier battled the wind brilliantly at the notoriously difficult Valderrama to card a 67, 11 shots better than Rahm, who was in a tie for 107th at seven over.
The US Open champion now faces a fight just to make the cut in his second consecutive event on home soil after finishing in a tie for 17th as two-time defending champion at last week’s Acciona Open de Espana.
Guerrier’s time in Spain has been more fruitful, with the 36-year-old claiming a top-three finish last week to virtually assure his place on Tour next season.
He carded six birdies and two bogeys to get to four under on day one at the 1997 Ryder Cup venue and admitted he was enjoying playing with less pressure on his shoulders.
“I think I’m more relaxed,” he said. “I’m playing to shoot a low score, not save my card, that’s the main thing. We work every day, improve our game and it’s working at the end of the year.
“It was really complicated today. The wind was growing stronger on the back nine.
“I had two bogeys on the score card, very few, and six birdies. It’s good to have six birdies in these conditions.”
Last week's winner Rafa Cabrera Bello was his nearest challenger at three under, a shot clear of Frenchman Romain Langasque.
England's Andrew Johnston – a winner over this layout at the 2016 Open de Espana – was one under, a shot ahead of countrymen Matt Fitzpatrick, Daniel Gavins, David Howell, Matthew Southgate and Paul Waring.
Bangor's Jonathan Caldwell carded a one-over 72 that included four bogeys and three birdies, good enough for a share of 22nd position.
British and Irish unless stated, par 71 - Play suspended due to darkness with one player still to finish
67 Julien Guerrier (Fra)
68 Rafael Cabrera Bello (Esp)
69 Romain Langasque (Fra)
70 Sebastian Soederberg (Swe), Joachim B. Hansen (Den), Ryan Fox (Nzl), Wil Besseling (Ned), Andrew Johnston, Soeren Kjeldsen (Den)
71 Matthew Fitzpatrick, Pablo Larrazabal (Esp), David Lipsky (USA), Paul Waring, Daniel Gavins, Renato Paratore (Ita), Alejandro Canizares (Esp), Matthew Southgate, Tapio Pulkkanen (Fin), David Howell, Adrian Meronk (Pol)
72 Aaron Rai, Thorbjoern Olesen (Den), Sami Valimaki (Fin), Alexander Bjoerk (Swe), Haotong Li (Chn), Ignacio Elvira (Esp), Jonathan Caldwell, Sebastian Garcia (Esp), Thomas Detry (Bel), Zander Lombard (Rsa), Scott Jamieson, Joakim Lagergren (Swe), Nino Bertasio (Ita), Julian Suri (USA), Ashley Chesters, Robert Rock, James Morrison
73 Min-Woo Lee (Aus), Bernd Wiesberger (Aut), Nicolai Hoejgaard (Den), Jorge Campillo (Esp), Joost Luiten (Ned), John Catlin (USA), Robert MacIntyre, Adrian Otaegui (Esp), Graeme Storm, Michael Lorenzo-Vera (Fra), Jason Scrivener (Aus), Jordan Smith, Masahiro Kawamura (Jpn), Richie Ramsay, Oliver Wilson, Alvaro Quiros (Esp), Fabrizio Zanotti (Pry), David Horsey
74 Laurie Canter, Connor Syme, Martin Kaymer (Ger), Justin Harding (Rsa), Grant Forrest, Callum Shinkwin, Kristoffer Reitan (Nor), Santiago Tarrio (Esp), Wilco Nienaber (Rsa), Eduardo de la Riva (Esp), Matthias Schwab (Aut), Gavin Green (Mal), Sean Crocker (USA), Jeff Winther (Den), Maximilian Kieffer (Ger), Lorenzo Gagli (Ita), Matthieu Pavon (Fra)
75 Richard Bland, Nicolas Colsaerts (Bel), Marcus Kinhult (Swe), Lucas Bjerregaard (Den), Ashun Wu (Chn), Alexander Levy (Fra), Kristoffer Broberg (Swe), Marcus Armitage, Antoine Rozner (Fra), David Law, Thomas Bjorn (Den), Edoardo Molinari (Ita), Peter Hanson (Swe), Marc Warren
76 Chris Wood, Mikko Korhonen (Fin), Stephen Gallacher, Richard McEvoy, George Coetzee (Rsa), Thomas Pieters (Bel), Pep Angles (Esp), Laird Shepherd, Jack Senior, David Drysdale, Oliver Fisher
77 Daniel van Tonder (Rsa), Marcel Siem (Ger), Gonzalo Fernandez-Castano (Esp), Benjamin Hebert (Fra), Adria Arnaus (Esp), Kalle Samooja (Fin), Jazz Janewattananond (Tha), Francesco Laporta (Ita)
78 Jon Rahm (Esp), Steven Brown, Victor Perez (Fra), Andrea Pavan (Ita), Scott Hend (Aus), Eddie Pepperell, Ross McGowan, Ross Fisher, Victor Dubuisson (Fra), Jamie Donaldson
79 Shubhankar Sharma (Ind), Javier Ballesteros (Esp), Justin Walters (Rsa)
80 Andy Sullivan, Michael Campbell (Nzl)
81 Guido Migliozzi (Ita)
82 Chris Paisley, Haydn Porteous (Rsa), Gaganjeet Bhullar (Ind)
83 Joel Stalter (Fra)