Play was suspended on Friday due to inclement weather but the re-start time was pushed back dramatically on Saturday as damp conditions and the threat of dangerous weather persisted.
When play finally resumed, and tournament officials had already made the decision to reduce the event to 54 holes, Park's lead, which he established Friday with a 64, remained.
Local favorite Jose Maria Olazabal completed a round of 69 on Saturday to stand alongside first-round leader Damien McGrane at 5-under-par 135 in second place.
'It was nice to play well and steady after such a long delay,' said McGrane. 'That must have been the longest round of my life.'
Should Olazabal win on Sunday it would be his first title of 2003.
'My goals this week, and next week in the Open de Madrid, are to finish well so that I can get into the Volvo Masters and also to get some feel back into my game,' said Olazabal. 'I don't feel in control of my swing although I have done a good job this week.'
Benn Barham, Henrik Stenson, Marcel Siem, Jose Manuel Carriles, Ricardo Gonzalez and Maarten Lafeber, who won last week's Dutch Open, shared fourth place at 4-under-par 136.
Mark Foster, Gary Emerson, Miguel Angel Martin, Markus Brier, Jose Manuel Lara, Jamie Spence, Sion E. Bebb, Charlie Wi, James Hepworth and Warren Bennett were one shot further back at 3-under-par 137.
Lee Westwood, twice a winner this season, carded a 1-under 69 to avoid missing the cut which fell at 3-over-par 143.
'Going out to finish the second round today, being at the bad end of the draw, it was quite tough to make an impression,' said Westwood, who finished at 1-over-par 141. 'I had given myself a lot of chances yesterday but didn't make the putts so you're never going to tear it up doing that.'
A total of 76 players qualified for Sunday's final round.