Wall, who finished 90th on this year's European Tour, shot a six-under- par 65. He moved to the front on 133 after the first-round leader, Hsieh Chin-sheng of Taiwan, dropped three strokes on the final three holes for a 70.
"I am a bit surprised to be in the lead," said Wall, who had three top 10 finishes on the 1998 European Tour.
Wall leads Hsieh by a stroke and is three ahead of Mark Brooks and Taiwan's Wang Ter-chang.
Tiger Woods had four straight bogeys in the second round of the Casio World Open in Ibusuki, Japan, yesterday. Woods shot a two-over-par 74 to be six strokes behind the leader, Hidemichi Tanakag.