Jordan Spieth’s historic quest for the grand slam remains a distinct possibility after the opening round of the British Open at St Andrews.

Never mind a lack of Old Course knowledge. Never mind coming in late to Scotland off a win at the John Deere Classic in the USA or the considerable hype surrounding him. Spieth just rolls on.

While the 21-year-old’s five-under 67 was somewhat overshadowed by playing partner Dustin Johnson’s 65, the Masters and US Open champion sits well poised to continue a historic year.

“I’m very pleased with the start. I saw a 65 in our group, and if DJ keeps driving it the way he is, then I’m going to have to play my best golf to have a chance,” Spieth said.

“It’s hard to argue with somebody who’s splitting bunkers at about 380 yards and just two-putting for birdie on five or six of the holes when there’s only two par-fives.

“I don’t have that in the bag, so I’ve got to make up for it with ball-striking.”

Looking to become just the second man to win the first three legs of the grand slam after Ben Hogan’s 1953 efforts, the Texan looked like he might streak clear early.

Just as he did at Augusta National in April, Spieth was flying in the early stages, getting to six under through 11 holes, but a couple of speed hump bogeys cooled his tilt.

It left him just two back of Johnson, the man he conquered at the US Open, one closer than after the first round a month ago at Chambers Bay.

He has now made an astonishing 53 birdies in 162 holes in the majors this year, almost one every three holes and was confident he could reel in the leader again.

“I think I can. If I didn’t, I would go ahead and walk off and take a flight back home tomorrow,” he said.

Aware the weather forecast shows heavy rains and winds in the second round, Spieth was especially pleased to make a final-hole birdie to make the most of the early benign conditions.

“To steal the one back from 17 and to shoot even par on the back nine, which once you turn into that breeze, is a good score,” he said.

“You need to put yourself in good position to have some shots to spare and not worry about a cut line or anything.

Speith said he was expecting a “brutal” Friday.

“We just don’t know when the rain is going to start, when it’s going to stop, if it’s going to come back.

“I think that tomorrow is a true Scottish day that we all should enjoy the challenge ahead, but today is certainly a big day to try and get off to a good start.”