The Englishman, who won the Taiheiyo Masters last week, joined the defending champion, Jumbo Ozaki, on 135, after a three-under second round of 68.
Ozaki, whose bogey-free round kept alive his hopes of a third consecutive victory in the tournament and his 100th career win, and Westwood are one shot ahead of the overnight leader Tom Watson after his 70.
Westwood's round included four birdies on the front nine, with the only blemish being a bogey at the par-four 14th hole.
Australia's Peter Lonard overcame a pre-dawn wake-up call yesterday to take a share of the lead in the Australian PGA championship in Sydney. He is joined on six under par, 138, by his compatriots Justin Cooper and Chris Gray.
Lonard was one of 53 players forced to rise early to complete their first rounds after strong winds disrupted Thursday's opening round.
Lonard, one of the first out on the course, finished his round on three- under par. He then had birdies at four of the first five holes of his second round to hold the outright lead before dropping a shot to finish equal with Cooper (68) and Gray (70).
American Jerry Kelly's 66 was the best round of the day and he joined the overnight leader Wayne Riley, of Australia, on 139. Gary Evans and David Howell were the best-placed British players on 143, with Ben Jackson slumping to a 77 after his opening-round 68.
Britain's Catriona Matthew and Laura Davies struggled to maintain their first-day form as Jane Crafter took the lead after the second round of the Australian Ladies' Masters on the Gold Coast.
Crafter, using a brand new putter, shot an eight-under-par 65 for a 12- under-par total of 134 and a two-stroke lead over Matthew, who added a 71 to her first-round 65.
Davies was a shot further back on 137 after an inconsistent second round of 70. The champion in 1993 and 1994 twice took three putts for bogeys but recovered by sinking a 40-foot eagle putt at the par-five 15th.
Scores, Digest, page 29