Four days after his near-miss at the British Open, Jason Day has exhibited no ill-effects from that Monday finish and his transatlantic flight to Canada.

The Australian world number nine checked in with a sparkling six-under-par 66 for a 10-under total to trail early second-round leader Chad Campbell of the United States by four shots at the RBC Canadian Open on Friday.

Brian Harman was alone at 12 under after firing a 67, finishing the round a stroke in front of fellow American Johnson Wagner (66) and Canadian David Hearn (64).

Graeme McDowell recovered from making a bogey and a double bogey in his first five holes to card a level-par 72 in his second round, but at three over will miss the weekend cut.

The 27-year-old Day believes he has plenty of time to rest up and also contend at the Canadian Open, despite all the travel and mental stress that comes after competing at a Major championship

“I’ve got five hours to play and 19 hours to rest,” the Australian told reporters. “So I’ve just got to suck it up. I’ve got two days left and then I can have a week off, so I’m just going to keep fighting until it’s over.”

Campbell was in outstanding form, hitting five birdies after starting from the 10th hole to turn in 32 and making four gains on the way home to take the clubhouse lead.

Graham DeLaet, the highest-ranked Canadian in the field, withdrew from his national championship during the second round on Friday because of a left thumb injury.

The 33-year-old from Weyburn in Saskatchewan jammed his thumb when he hit a tee shot on the 12th hole during Thursday's opening round at Glen Abbey.

DeLaet managed to finish with an even-par 72 and said he was hopeful that he could play through discomfort in the second round, despite experiencing pain on his takeaway.

However, the world number 84 lasted just four holes on Friday before deciding to quit.