Rory McIlroy's annus horribilis continues at Memorial Tournament in Ohio

Rory McIlroy is in danger of missing his second successive cut after carding a six-over-par 78 in the first round of the Memorial Tournament.

The world No 2's interest in last week's PGA Championship at Wentworth ended after two rounds, with the Northern Irishman blaming the unseasonably cold weather. He began the tournament at Muirfield Village, Ohio, positively, holing a 22-foot putt at the 10th – his first – for birdie.

But he double-bogeyed the par three 12th – his third – and followed that up with three more bogeys on his opening nine holes. There was more of the same on the back nine with three more bogeys and only a birdie at the fifth provided any respite.

McIlroy, who missed the cut at last year's Memorial before doing the same at the US Open two weeks later, said: "I'm pretty frustrated. I'm trying not to let it get to me. I don't have any explanations for it. I'm fully focused on what I need to do and I didn't think I played as bad as the score would say.

"I thought coming off the back end of last year, winning the PGA Championship, I wanted to do the same sort of things. It just hasn't happened. I haven't lived up to my own expectations."

Lee Westwood, who squandered a two-shot lead in the final round at Wentworth, did not fare much better, finishing the first day on four over par.

But neither McIlroy nor Westwood had as difficult an opening round as their Belgian Ryder Cup team-mate Nicolas Colsaerts, whose score of 80 included two triple-bogeys.

South Africa's Charl Schwartzel was the early clubhouse leader after round one, having shot a seven-under-par 65 – and his lead would have been greater than the one shot he is ahead of Scott Piercy of the US, if he had not carded a bogey and a double himself.

Matteo Manassero, the winner at Wentworth after a four-hole play-off, shared the first-round lead with Spain's Pablo Larrazabal at the Nordea Masters in Stockholm, after the Italian birdied his first six holes.