The latest glimpse of a return of Rory McIlroy’s mojo arrived over the closing stretch of the Scottish Open’s first round.

He has spoken of an understandable need to find new mountains to scale after Masters glory completed a career grand slam. On the 15th hole at the Renaissance Club, the Northern Irishman was in trouble; his fairway bunker shot had rolled back towards his feet. McIlroy’s ball sat in the mark created by his first attempt. “It served me right for trying to hit a nine-iron with the lip two feet in front of me,” he said later.

The response was notable. The world No 2 pitched out sideways, holed from 21ft – and the fringe of the green – for a bogey and rattled off three birdies in a row over the closing holes.

A 68 to start at the tournament which precedes McIlroy’s Open Championship tilt at Portrush was hugely impressive in context. He sits only four shots from the lead.

“It was a great finish,” McIlroy said. “The round was a bit stop-start, there was a little bit of rust in there after taking a couple of weeks off. I felt like I found my rhythm and started hitting better shots on the way in. It is the sort of course and these are conditions where the field will be pretty bunched so to be only four behind, feeling like I still have my best stuff ahead of me, is good.” The winner of five majors has the chance to make further impact from his early start on Friday.

McIlroy’s finish involved converted putts of 26ft on the 17th and 19ft at the last. His birdie at 16 was a straightforward one, the par five having been comfortably reached in two. He regards his game as 80% towards where it needs to be for Portrush. “I’m ready to play,” he added. “A change of scenery has been nice, getting back over here has sort of renewed my excitement and enthusiasm for the rest of the season.”

Colombia’s Nico Echavarría, Sepp Straka, Victor Perez and Jake Knapp head proceedings at six under. Marcel Siem is among those at minus five. The German, now 44, admitted he has toned down the heavy partying that sat alongside his golfing pomp. “I am not getting any younger,” said Siem. “I have to look after my body more now. I know I can stand on the range and hit golf balls, I’ve done it my whole life. But it’s more about recovery, sleeping well and not drinking.

“I think those days of drinking and playing golf are over unfortunately. There is a time and place for it. It’s nice to enjoy a few pints after a good result, for example. The problem is I’m not in training any more. Two years ago, if I have one or two beers for dinner, it’s fine. But I can’t do it any more. On Monday this week, I had two pints of Guinness and felt horrible the next day. I think I am getting too old to be drinking and playing golf.” Siem is hoping to earn an Open berth with a strong performance in East Lothian.

Viktor Hovland, playing in McIlroy’s company, signed for a 66. The world No 1, Scottie Scheffler, looked puzzled by the greens at various points but still produced a 67. “I wish I would have played a little bit better,” said the US PGA champion. “But overall, I felt like I did some good things out there and hung in there nicely and put up a decent score. I wish it was a little bit lower but not too bad of a first round.”

Scheffler played alongside the defending champion Bob MacIntyre, who made a 68. Justin Rose headed straight for the putting green after a level-par 70.