Matthew McClean of Great Britain and Ireland celebrates on the 18th green during the Saturday singles. Oisin Keniry/R&A

Yes, it is a game played outdoors in all kinds of weather. Yes, 18-hole matches are unpredictable sprints in which a hot putter can often be the springboard to a seemingly unexpected result. And yes, the inherent randomness of golf makes pre-emptive assumptions mere acts of folly. It’s all true.

OK, now forget all that stuff.

Sometimes, what is expected, predicted or foretold by so-called experts actually does occur.

OK, now forget that too.

Welcome to the opening day of the 49th Walker Cup at St Andrews, a time and place where all that is good about match-play golf was on show. A few matches were dominated by one side or the other. Some saw leads change hands multiple times. Others featured near-epic comebacks from sizeable deficits. Many could have gone either way.

All the while the overall momentum of the occasion shifted, providing almost endless interest and excitement for the large crowds walking the fairways — yes, on the fairways — of golf’s most famous course. Card-and-pencil golf might be the best way to determine winners/champions over 72 holes, but over 18 it is a no-contest; match play is the way to go.

Whatever, no matter how you look at things, with the score 7½-4½ in favour of the home team (equalling their biggest first day advantage since 1989), this remains a contest both teams will fancy their chances of winning. Certainly, both captains remain full of fighting talk.

“Obviously, a great day for us results-wise,” said GB&I skipper Stuart Wilson. “But this is still going to be a tight match. They started fast this afternoon. But our guys got some points ‘against the head’ later on. So, well done to my lads. They have proved that they can compete with the best. There were so many close matches out there. And a lot of strong numbers. So, we’re taking nothing for granted. A putt here and there can make such a big difference.”

Understandably, US captain Mike McCoy was a little more subdued. But with 14 more points to play for on Sunday (10 singles will conclude proceedings after four morning foursomes) the contest isn’t even half done. So much remains to be played for, a fact McCoy was keen to underline.

“It wasn’t the day we were looking for,” admitted McCoy. “The afternoon did start the way we wanted and guys got up early, but we didn’t close those matches. A couple slipped away. But we will regroup. … The course is likely to play more difficult. So, our players will need to step up and give us an opportunity.”

Remarkably, World No. 1 Gordon Sargent and his foursomes partner, Dylan Menante (who did not play in the singles), are the only Americans who didn’t lose a match on a day when all 10 teed up at least once. Of the other eight, US Amateur champion Nick Dunlap will surely have the biggest sense of anti-climax. Just three weeks on from claiming his national title, the Alabama native lost by a whopping 6&5 margin to Englishman John Gough.

“We knew what we had to do this afternoon,” said Sargent, who came from 1-down with two to play to defeat Jack Bigham. “We weren’t really down at lunch. We knew that we didn’t play bad golf. They played well and hats off to them. But we knew singles was where we could take advantage.”

So much for that theory.

In contrast to the American travails, only two of captain Wilson’s men — Bigham and Barclay Brown — have yet to add at least a point to the GB&I total. And much to the glee of the home crowd, the two Scots in the side, 16-year-old Connor Graham and Calum Scott, are unbeaten. The pair combined to win their morning foursome before Scott went on to defeat Nick Gabrelcik 2&1.

None of which appeared likely 24 hours earlier. The US side had been called “vastly superior”, “deeper from top to bottom” and “likely to win handily” in what is golf’s oldest biennial contest.

OK, forget that too.

Down 3-1 after the morning foursomes, the powerful-looking American squad — one containing eight of the top 10 in the World Amateur Rankings — lost the afternoon singles 4½-3½.

Released from the unfamiliar constraints and pressures of foursomes golf, one-on-one the American squad was supposed to own a depth the opponents wouldn’t be able to match. But all was very different as gloriously warm sunshine and light breezes cooled golf’s most famous venue only slightly.

A final thought. After all of the above, perhaps the only safe prediction for day two is that anything might happen.