Rory McIlroy bounces back to form in the Memorial Tournament

Just two days after tournament host Jack Nicklaus had lamented McIlroy's occasional lapses in concentration, the four-time major winner carded a triple bogey on the 18th to card a level-par 72.

"I don't know whether his is a constant lack of being able to keep that concentration for the whole thing or not, because sometimes he (goes) par, par, par, double, eight," Nicklaus said in his pre-event press conference. "He does that sometimes."

It was not an eight on Thursday but a nevertheless destructive seven on the par-four 18th, where his drive finished in deep rough on a steep side slope.

McIlroy could only hack his ball almost sideways into more rough and he caught a flier with his third before taking four shots to get down from the back of the green.

"I felt good about everything that I did yesterday," McIlroy said after carding six birdies and two bogeys in a second round of 68. "I got one bad break on 18 with that ball finishing on the bank of the bunker. So I really feel like I'm one shot out of leading this golf tournament.

"(If) that rolls down into the bunker, hopefully I'm able to hit it on the green and make a four and instead of standing here at four under I would be at seven under and feeling really good about everything.

"I felt like I did a lot of really good things yesterday and I did a lot of good things right, so I can't let that one sort of unlucky break sort of hide the fact that everything else was working pretty well."

At four under par McIlroy was three shots off the early clubhouse lead held by Hideki Matsuyama, the former Masters champion carding a superb bogey-free 65.

l Scotland’s David Law produced a “pretty unbelievable” second round to lie a shot off the halfway lead in the Porsche European Open in Hamburg.

Law tamed a 7,455-yard course known as the Green Monster as he fired an eagle and eight birdies in a seven-under-par 66.

That drew high praise from the man at the top of the leaderboard, Germany’s Max Kieffer adding a 71 to his opening 69 to reach six under par, a shot ahead of Law, Jordan Smith and Northern Ireland’s Tom McKibbin.