Though Justin Thomas and Lee Westwood, who finished eagle-birdie-birdie, are among those chasing him, it could be a case of how many shots the Spaniard will win by, not can he, if he keeps it up on the East Lothian coast.
On a day that made him feel at home, both in the Basque Country and his beloved Torrey Pines in California, as mist rolled in over the Tom Doak-designed course following a glorious sunny start, Rahm continued to revel in his new world No 1 and major champion status.
Shrugging off an astonishing incident before getting underway as a spectator appeared on the tee at the 10th hole and grabbed a club out of playing partner Rory McIlroy’s bag before being hustled away by a security guard, the 26-year-old breezed to the turn in 29.
After starting for home by picking up his seventh birdie of the round, Rahm had suddenly opened up a four-shot lead over the strongest-ever field for the $8 million Rolex Series event and you really did fear for the chasing pack, even at that early point in the proceedings.
He then dropped two shots in the space of three holes as the wind switched to the east and had to settle for a level-par score on the inward journey, but, nonetheless, this has already had the makings of another ominous start from Rahm.
“Those first 10 holes I played incredible,” said the man who was 18-under-par for 54 holes and leading by six shots when told that he’d have to withdraw from the Memorial Tournament on the PGA Tour last month due to testing positive for Covid-19 before bouncing back to win the US Open after he’d come out of isolation. “The three pars I had were short putts that could have been made. They were clearly birdie chances.
“That’s not always going to happen. There were moments of luck, too. If my second shot on 16 (his seventh hole) went two yards further than it did, I would have had no shot to the pin. There were a couple of others like that. It was good golf combined with good luck.
“When the wind picked up as we played holes two through to five, the starting line changed, so I feel like it was a little bit of adjustment in that sense. I was playing some holes in a wind I had never played before.
“I got a little hesitant. I made some aggressive swings without thinking about it as much as I could have because I was playing so well and maybe could have taken a step back.”
Rahm is a two-time Irish Open winner and now has a fifth Rolex Series title in his sights, sharing the lead at the mid-point on Scotland’s Golf Coast with Belgian Thomas Detry and Englishman Jack Senior, with Westwood, Matt Fitpatrick and George Coetzee all a further shot back.
“Swing-wise it’s good. If I just clean up some little mistakes, it could be better,” added Rahm of his week’s work so far, with the season’s final major, the 149th Open at Royal St George’s, next up after this assignment.
While a haul of 15 birdies here so far has been pleasing, so, too, have par-saving shots like the one from a greenside bunker to a tight pin position at the ninth - his closing hole – in the marquee group alongside McIlroy and Justin Thomas.
“It was very pleasing,” he said of that effort. “It’s not an easy par-3 and when we got there the wind picked up a bit. I started the ball five yards right of where I was looking and it could have been a really bad spot. But the wind was helping the shot.
“The ball was above my feet, so I could be aggressive coming out of the bunker. I would have taken six feet, but it was inside three feet. It felt more like a birdie than a par.”
Detry, who had “great vibes” about this week after shooting a 64 on the final day here last year, crossed swords with Rahm in their amateur days.
“We played many times, mainly in the Palmer Cup and we won when Andrew Coltart was the captain,” he recalled. “Jon is a great guy. He’s No 1 now, but he’s still like my friend.”
Senior, the overnight leader after his opening 64, made it a three-way tie at the top as he came in late in the day with a card containing five birdies to maintain his surprise presence in the title hunt.
Westwood, who played regularly here when he lived in Edinburgh for a spell, transformed his day with a sensational finish, which was sparked by leaving himself a tap in for an eagle at the 16th following a majestic 4-iron from 246 yards.
“That will make dinner taste sweet tonight,” declared the European No 1 of then following that by holing an 18-footer for a 2 at the next then rolling in one from slightly further away for a 3 to finish.
Thomas, the world No 3, sits in a group on eight-under that also includes David Law and Ian Poulter, with Europe’s Ryder Cup captain Padraig Harrington and American Scottie Scheffler among those a shot further back, the latter having catapulted himself up the leaderboard on the back of a blistering 63.
Rory McIlroy, who missed out by a shot on one-under, was the biggest casualty, while fellow major winners Martin Kaymer, Henrik Stenson and Graeme McDowell also suffered early exits.
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