It looked, for a moment, as if Stuart Broad had his third wicket and it looked, for a moment, as if South Africa had subsided to 86 for 4.
The delivery, a brute of a ball, had climbed on Rassie van der Dussen and taken his glove. England celebrated. It appeared Broad, revelling in the uneven bounce available to him from the Wynberg End, may be on the brink of one of those spells.
But then came the replays. And after that the realisation that Broad had become the latest bowler to see a wicket squandered after the umpire belatedly signalled a no-ball. Van der Dussen, who had been on 16 at the time and given quite the send-off by James Anderson, made his way back to the wicket, went on to make 68 and, with Dean Elgar, add 117 for the fourth-wicket. It could still prove to be a pivotal moment in this Test.
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The initial reaction to such moments is probably frustration with the bowler. And, ultimately, they probably do have to take responsibility.
But maybe they are also due some sympathy. For in recent times, on-field umpires in international cricket have all but abandoned calling no-balls. Modern bowling is so fast, modern batting so powerful that umpires often stand well behind the stumps - Paul Reiffel was every bit of six feet behind them when Broad was bowling - with their eyes trained on where the ball is pitching and hitting. As a result, modern thinking suggests they shouldn't worry too much about no-balls. It's probably understandable but there were fast bowlers and powerful batsmen in the past. Umpires have still managed to check for those no-balls.
Anyway, while this may seem, at first glance, like a piece of fortune for the bowler, it is probably exactly the opposite. For if the on-field umpire stops calling no-balls, the bowler can be lulled into a false sense of security about where their foot is landing. Instead of taking the chance to correct themselves before it costs them a wicket, they might repeat the error numerous times.
Certainly that's how it seemed here. The delivery before the van der Dussen incident should also have been called as a no-ball - replays showed Broad had overstepped - and a short while later, Ben Stokes bowled three or four no-balls in an over. None of them were spotted by the on-field umpire.
Shaun Pollock raised an interesting idea on TV commentary. He suggested the square leg umpire could relocate to be square at the non-striker's end and therefore be the individual responsible for monitoring no-balls. Historically the square-leg umpire might have adjudicated for stumpings and run-outs but, in the days of TV replays, that isn't so relevant. At international level, at least, Pollock's idea would seem to have plenty of merit. Equally, however, you would think the TV umpire might be able to check the front foot every delivery.
Ultimately, though, the players - and the coaching team - have to take responsibility. And while England's ODI squad have proved they can all but eradicate overstepping - they famously went more than 10,000 deliveries without conceding a front-foot no-ball in ODI cricket - in Test cricket it continues to hurt them. Consider, for example, Jack Leach's 'dismissal' of Steve Smith on 118 at Old Trafford - Smith went on to make 211 after replay showed Leach had overstepped - or the fact that Mason Crane, Ben Stokes, Tom Curran and Mark Wood all thought they had taken their first Test wickets only to have them withdrawn after replays showed they had bowled no-balls.
Perhaps there has to be more rigour involved in training sessions, too. It is, at present, routine to see England's bowlers overstepping in the nets. Instead of getting into good habits, grooving their run-up so it eradicates such faults, they invariably bowl several inches over the line. With such a large touring party, there is no reason England could not have unofficial umpires involved in net sessions calling the bowlers for no-balls as required. Equally, the fielders at mid-on and mid-off might keep an eye on their bowlers' front feet and let them know if they are in danger of overstepping.
Equally, England do not currently have a full-time specialist bowling coach with them following Chris Silverwood's promotion from that position to the head coach role. There are rumours that Jon Lewis, the former Gloucestershire seamer who is now coach of the England Under-19 side could get such a job - he has a strong relationship with Jofra Archer, which is probably helpful - but for now it remains vacant.
James Anderson has shown what can be achieved. He has bowled 40 no-balls in his entire Test career - which is pretty impressive given he's bowled more deliveries than any other seamer in history but, since the Adelaide Test of 2013 - more than 2,000 overs ago - has bowled only four. If he can do it, so can the others.
Despite the no-ball episode, England could feel well satisfied with their day's work. Broad enjoyed the bounce, Anderson struck twice with the second new ball and Sam Curran claimed two big wickets with the old ball. The dismissal of Quinton de Kock, fooled by a slower ball, would have been particularly pleasing.
And while the figures may look underwhelming, Dom Bess enjoyed a really good day. His job, in these circumstances, was simply to bowl dry at the end offering bowlers little assistance and allow his captain to rotate the seamers from the other end, which offered some variable bounce. He did it well, too, conceding around two-an-over for most of the day and gaining the bonus wicket of Dean Elgar when he tried to disrupt England's plans. For a 22-year-old called up at short notice, it was a performance that spoke volumes for his character as much as his skill.
In no small part thanks to him, England have their noses in front in this match. On a pitch already offering a bit of variable bounce, batting last might be prove tricky and South Africa would have hoped for a sizeable first innings lead. Had Broad not overstepped, however, England's advantage would be significantly greater.