Rory McIlroy made an ideal start and put personal worries aside as he attempts to secure an overdue fifth major title in the 106th US PGA Championship.

Following a 10-minute delay to the start of play due to lingering patches of mist at Valhalla, McIlroy got his campaign under way on the par-five 10th and hit a well-controlled pitch to six feet to set up an opening birdie.

The world number two had understandably refused to talk about his private life in his pre-tournament press conference, which came the day after it emerged he had filed for divorce from his wife of seven years, Erica, on Monday.

The timing could not have been worse given McIlroy had won the Wells Fargo Championship for a fourth time just hours earlier, a second victory in succession following his win alongside Shane Lowry in the Zurich Classic.

Coincidentally that mirrored the form McIlroy enjoyed in 2014, when he followed his victory in the Open at Royal Liverpool with another in the WGC-Bridgestone Invitational before travelling to Valhalla and securing back-to-back major wins in dramatic circumstances.

Related: Four holes to watch at this year’s PGA Championship

John Ballard, superintendent at Valhalla, was asked for his thoughts on four key holes for this year's event.

Birdies on the 13th and 17th gave McIlroy a two-shot lead in a final round delayed by almost two hours due to thunderstorms and, with daylight fading fast, the penultimate group of Rickie Fowler and Mickelson had to be persuaded to stand aside to allow McIlroy to tee off on the 18th.

Mickelson came agonisingly close to holing the eagle chip he needed to potentially force a play-off and McIlroy’s par from a greenside bunker sealed a second major win in the space of 21 days.