The two-time major champion and pre-tournament favourite needed a par putt at the 18th hole just to make the weekend's play with a five-over-par second-round 77 sneaking him the right side of the halfway cut at four over after 36 holes.

That leaves McIlroy 11 shots off the pace being set by 2012 Masters champion Bubba Watson, who shot a 68 on Friday to open up a three-shot lead over the rest of the field.

“Anything in the 60s is a really, really good score out here,” McIlroy said on Friday night having completed his round in the final group of the day. “And it will take something phenomenal to shoot something in the mid-60s and get myself back under par going into the last day. But I'm going to need to be two, three, four under par going into the last day to have any sort of chance.”

That may be a tall order for Ireland's leading light given his difficulties during the second round. He had started at one under par with the breeze picking up and McIlroy bogeyed the par-five second, birdied the par-four third and had an eventful negotiation of the par-three fourth.

His tee-shot wood carried on the wind, overshooting the 240-yard hole as well as the fifth tee box behind it, McIlroy's ball just missing defending champion Adam Scott as the Australian eyed up his tee shot in the group ahead, before hitting the perimeter fence, going out of bounds.

With a referee by his side, the Ulsterman considered taking an unplayable lie but rather than playing out of the bushes, he went back to the fourth tee for his third shot, this time deploying a four iron. Too late to repair the damage, he took double bogey.

The topsy-turvy nature of McIlroy's round continued, though, with a birdie at the fifth before consistency return for the two-time major winner to par his way to the turn, albeit with a birdie chance going begging with a missed putt at the eighth.

Putting was McIlroy's headache all day and having dropped shots with a double at the 10th and bogeys at 11 and 13, where his approach flew off a sprinkler head and up into a forest of azaleas behind the green.

At four over par on the 18th green, McIlroy had two putts to get into the weekend, starting from the top tier and rolling his first effort down the slope to five feet past the hole. It still left him with plenty to do but the major champion held his nerve, sinking the putt to tee it up in Saturday's third round.

“It was very frustrating,” McIlroy said. “I just really couldn't get anything to go my way. I had a couple of really bad breaks on four and 13. Got a really massive wind switch on four. And then hitting the sprinkler on 13 to go up into the azaleas.

“I felt like I played well coming in. I gave myself looks at birdie almost every hole. I couldn't get one to drop. Felt like I had good putts and they were either hitting the high side of the hole or low side of the hole. Just nothing but going in.”

Eleven shots is not an insurmountable deficit and with the field so compressed there are 51 survivors all with a chance of victory come Sunday night. McIlroy though, will need to get a move on and even then hope for the leader to come back to the pack.

Watson, though, will have other ideas and following his second round 68 spoke of being unburdened by the pressures of being a defending champion.

It was left-hander Watson who two years ago gave golf a jolt in the arm with his spirited and creative approach to this most traditional of sporting arena, winning his first major courtesy of a miraculous, right-angled hook out of the pine straw at the 11th hole to win a play-off at the second hole from Louis Oosthuizen and bag himself a green jacket.

A year on, the responsibilities that fall on a Masters champion took their toll with Watson admitting the experience was “overwhelming”, the product of which was three over-par rounds including a closing 77 in a title defence that finish in a tie for 50th place.

It would not be until this February that Watson experienced victory again, at the Northern Trust Open in Los Angeles. With two top-10s having followed since, another victory is in the American's sights back at the Masters, especially after a second-round 68 that featured a run of five consecutive birdies on the back nine, only a bogey on 18 pegging him back to seven under at the midway point.

After benign weather during the first round, the more difficult conditions on day two made the Amen Corner complex of holes at 11, 12, 13 particularly difficult to negotiate as the wind swirled above the azaleas.

It was precisely there, however, that Watson's round came to life. He had started the day in a tie for second at three under with defending champion Scott and Oosthuizen, a shot behind overnight leader Bill Haas, and had turned for home even for the day, despite dropping his first shot of the week at the par-four ninth.

It was at the par-three 12th that the Watson fireworks began, a great iron shot off the tee to within two feet of the pin setting up a birdie that put him into a share of the lead with Haas and a fast-starting Kevin Stadler, who had started the day at two under.

Pumped up by the birdie, Watson will have approached the dogleg left par-five 13th with a glint in his eye and he launched a massive drive over the trees on the corner and across the fairway en route to a birdie four.

They kept coming, Watson completing his run at the 16th with a wonderful nine-iron tee shot over the water for the one-putt birdie that took him to eight under.

Watson had put some daylight between himself and the field as the Masters got its first clear leader but trouble struck at the 18th when sliced his second shot into the left gallery. He pitched up nicely but then had to watch his par-save putt dribble past the cup.

Watson is three clear of Australian John Senden, with Scandinavian duo Thomas Bjorn of Denmark (68) and Sweden's Jonas Blixt (71) on three under alongside Scott, 1992 champion Fred Couples and Masters debutant Jordan Spieth.

Haas fell away with a 78 with Oosthuizen carding a three-over 75 that leaves him on level par.

There were mixed fortunes for McIlroy's fellow Irish major winners in the field with Darren Clarke posting his second two-over 74 yesterday morning and at four over sneaking into the weekend with the course and conditions toughening later in the day and sending many better positioned than the 2011 Open champion at the start of the day outside either the top-50 and ties with Watson's late surge to seven under cutting off the escape route of the 10-shot rule for many others.

If that was Clarke's good fortune, it was Graeme McDowell's downfall, his solid opening-round of level par unravelling last night as early as the opening hole, which he double-bogeyed. McDowell finished six over par to suffer his second consecutive missed cut at Augusta National.