Butch Harmon credits Rory McIlroy for opening round resolve at Royal Birkdale

Butch Harmon was full of praise for the strength of character that Rory McIlroy showed in salvaging some form in his opening round at The 146th Open at Royal Birkdale.

McIlroy, who has missed his last two cuts at the Irish Open and Scottish Open, suffered a terrible front nine shooting a five-over 39 but came storming back on the inward nine with four birdies to finish the day with a one-over 71.

The four-time major winner will go into Friday's second round with renewed optimism of lifting the Claret Jug for a second time and hopeful of further narrowing the deficit to the first-round leaders, Brooks Koepka, Jordan Spieth and Matt Kuchar, at five-under par.

"It just goes to show you, it's not how you start, it's how you finish that really matters and what I think is it shows a tremendous amount of heart today," said Sky Sports analyst Harmon.

McIlroy opened his first round with a bogey five which could have been worse had he not held a lengthy putt across the green but Harmon highlighted the par save at eight as being an integral moment in his revival of confidence down the stretch.

"I think that was the pivotal moment of his day," said Harmon. "If he misses that who knows what else is going to happen."

Royal Birkdale only has two par fives on the golf course but the European Ryder Cup star took full advantage with birdies at the 15th and 17th.

"He had to take advantage of those two par fives," added Harmon. "He had to turn this round around and fortunately for him the two par fives came towards the end of the round."

The Northern Irishman finished his round in grandstand fashion with a birdie to move to one over and sits six shots behind the three American leaders.

"This was the bonus of bonuses," said Harmon. "That [putt] could have ended the run - he could have had a tough time. "A perfect second shot and an even better putt and from 76 [or 77] to 71 and right back in this competition."

Meanwhile, Harmon was full of praise, aside for the two-time major winner's determination, for Spieth's consistency on the greens during his blemish-free five-under 65.

"The other thing he has [apart from his competitive nature] is he is probably the best putter in the game at the moment," said Harmon.

"When you have that, your confidence builder, you can save so many shots."