Irishman Padraig Harrington carded a 3-under-par 67 to grab a share of fourth place. He is joined there by Desvonde Botes, Michael Campbell, Kim Felton, Barry Lane, Edward Loar, Prayad Marksaeng and Lian-Wei Zhang.
The 24-year-old McEvoy, who was in the first group of the afternoon tee times, jumped out of the gate at Hong Kong Golf Club with birdies on two of his first four holes.
The Englishman caught fire around the turn. He birdied the eighth to begin a stretch of three straight birdies to move to 5 under. He continued his move with a birdie at the 12th.
However, McEvoy stumbled to his lone bogey of the day at the par-4 13th. He responded in fine fashion by rolling home back-to-back birdies to move to 7 under.
McEvoy, the medalist at the 2003 European Tour Qualifying School Tournament, capped his round by rolling home a 15-foot birdie at the last to finish one stroke off the course record.
Johl also began his day on the front side. He birdied the third and came back with consecutive birdies from the seventh to climb to minus-3.
On the back side, he drained birdies on Nos. 10 and 13 to get to 5 under. But he faltered to a bogey at the 14th. He recovered from that mistake to birdie the par-4 17th. However, he dropped a shot at the last to drop back into a second-place tie.
O'Hara, a teammate of McEvoy's on the winning Great Britain and Ireland Walker Cup team in 2001, meanwhile opened his round with a birdie at the 12th. He drained back-to-back birdies from the 16th to get to 3 under.
He climbed to 5 under with birdies at the third and the sixth, but fell back a stroke with a bogey at the eighth.
A healthy group of 17 players are tied at 2-under-par 68. Among those players sharing 12th place are Darren Clarke, Jose Maria Olazabal and defending champion Fredrik Jacobson.
'I am quite happy,' said Jacobson. 'I had a tough start, I thought I played all right but didn't make any of the chances I had in the beginning. It didn't happen, but then suddenly I made a bunker shot and a putt from 50 feet and that got me back into it a little bit. I think I am in a good position now.'
Thomas Bjorn, Ian Garbutt and Nick Faldo are in a large group one stroke further back at minus-1.