Christian Cevaer carded a 3-under 67 to climb into second place at 7-under-par 133. Peter Hedblom is one stroke further back after a 66 on Friday.
Henrik Nystrom, who shot a 65, shares fourth place at 5-under-par 135 with David Lynn, Jean-Francois Remesy and Marcel Siem, who each shot 68s.
Park started on the back nine and was steady to begin his round. He parred each of his first six holes before getting on the board with back-to-back birdies from the 16th at Fuerteventura Golf Club.
The Welshman parred the next two holes around the turn. Park dropped in his third birdie of his round at the second and came right back with a birdie at the very next hole. Park dropped a shot at the fourth when he was unable to save par from a fairway bunker.
Park bounced back from the error with a birdie at the fifth that got him back to minus-10. After a par at the sixth, Park sank a birdie on No. 7 before parring his final holes.
Park credits the work he has done with his swing coach on his early success this week.
'We had a week off after Portugal and we started working on it then but it is something I have to do for the rest of my life really because old habits die hard, don't they?' said Park. 'It is one of the first things that I worked on with Tim (Barter) when we started together. We have made great progress but I tend sometimes to go back to instinct if I don't monitor it.'
Cevaer got off to a good start with three birdies over his first seven holes. However, he bogeyed two of his next three to drop back of the pace.
The Frenchman got one of those strokes back with a birdie at the 11th. He came back with his final birdie, a chip-in from 20 feet out, two holes later. Cevaer parred in to remain alone in second place.
'I chipped in for eagle yesterday and another for birdie today so these are nice things to get,' said Cevaer. 'With this wind, you are going to have your share of holes where it is not easy so there are times where you have to hang in there and accept it is not always going to go your way. You work hard in this job and go through a lot of frustrating stretches, so you should really welcome any success you have.'
Julien Clement and Gregory Havret posted matching rounds of 7-under 63 to climb to 4-under-par 136. They are joined there by Marcus Fraser (68), Santiago Luna (67) and Miles Tunnicliff (66).
Roger Chapman, Klas Eriksson, Ricardo Gonzalez, Jose Manuel Lara, Miguel Angel Martin and Jose Manuel Carriles are one stroke further back at minus-3.
The cut line fell at 3-over-par 143. Among those who missed the cut were Malaysian Open winner Thongchai Jaidee (144), Spaniard Jose Maria Olazabal (146) and Jean Van de Velde (148).