Madrid - Home favourites Jon Rahm and Rafa Cabrera Bello were outshone by Norway's Kristian Krogh Johannessen on the first day of the Spanish Open on Thursday.
Rahm is the defending champion after his brilliant victory last year at the National Golf Centre and also chasing victory in the Race to Dubai, where he currently places second.
But while he and Cabrera Bello were among five players to come in five under in Madrid, Johannessen stole the show after pulling off four birdies in his last six holes to finish eight under.
Another Spaniard Adri Arnaus was one shot closer at six under while Italy's Andrea Pavan and German Marcel Siem were the other players three behind.
Johannessen's 63 for the round was the lowest of his European Tour career to date and would have been the lowest in the event's history had preferred lies not been in effect.
Spain's national tournament, which began in 1912, was back at the Club De Campo Villa De Madrid for the first time in 23 years and also welcomed back Sergio Garcia, whose debut in the competition came as an amateur in 1995.
Arnaus set the pace by hitting birdies on four of the back nine and an eagle at the 14th before Cabrera Bello and Rahm also picked up gains in that half of the course to come in one back.
But they made mistakes that Johannessen avoided, the 24-year-old clinching consecutive birdies at the fourth and fifth, and again on the seventh and ninth. An eagle on the 15th had been nullified by a bogey on the 16th but he immediately picked the shot back up.
Zander Lombard, Jason Scrivener, Samuel Del Val, Nicolas Collaterals, Siwan Kim, Manjeet Bullard and Adrian Taegu will all start the second day four shots off the lead on Friday.
Leading and selected Spanish Open first round scores at the Club de Campo in Madrid on Thursday (GNR/IRL unless stated, par 71):
63 - Kristian Krogh Johannessen (NOR)
65 - Adri Arnaus (ESP)
66 - Dean Burmester (RSA), Jon Rahm (ESP), Andrea Pavan (ITA), Jamie Donaldson, Marcel Siem (GER), Rafael Cabrera-Bello (ESP)
67 - Sihwan Kim (KOR), Matthew Nixon, Nicolas Colsaerts (BEL), Zander Lombard (RSA), Samuel Del Val (ESP), Jason Scrivener (AUS), Gaganjeet Bhullar (IND), Adrian Otaegui (ESP), Jens Dantorp (SWE)
68 - Steven Brown, Niklas Lemke (SWE), Wu Ashun (CHN), Matteo Manassero (ITA), Jack Singh Brar, Deyen Lawson (AUS), Jake McLeod (AUS), Chris Hanson, Miguel Angel Jimenez (ESP), Eduardo De La Riva (ESP), Per Langfors (SWE), David Lipsky (USA)
69 - Justin Harding (RSA), Ross Fisher, Javier Colomo (ESP), Lee Slattery, Joachim B. Hansen (DEN), David Drysdale, Sergio Garcia (ESP), Calum Hill, Justin Walters (RSA), Mario Galiano Aguilar (ESP), Nino Bertasio (ITA), Edoardo Molinari (ITA)