Most afternoon starters were still on their front nine when play was suspended for the day because of lightning. They will finish their round early Friday.
Olesen carded five birdies to end his second round at an overall 12-under 132. Levet had four birdies and two bogeys for a 70 and was 135 overall.
''I've been playing well for the past few months really, so I don't see any reason why I shouldn't win,'' said Olesen, who earned his first European Tour title at the Sicilian Open in April and has five more top-10 finishes this season, including at last week's British Open.
Pablo Larrazabal, who opened with a 64 on Wednesday, bogeyed both the par-3 fifth and ninth holes. The Spaniard was 2 over for the round when play was stopped.
Wiesberger shot six birdies for a 66, the lowest second-round score among the top players so far.
Defending champion Kenneth Ferrie of England carded a 73 to go 143 overall, 11 strokes behind Olesen.