Cricket is full of oddities. Who would have thought, for example, that James Anderson, after bowling so well in this one-day series, would suddenly go for 19 runs in his first over yesterday? After two overs for 24 he was taken off. When he came back for his second spell he took 3 for 1 in three overs as South Africa fell from 65 for 1 to 104 for 7 in a game where the main goal was to win the psychological advantage for Saturday's final at Lord's.
The most extraordinary moment of all, which will probably end up as no more than a temporary hiccup, although it could just prove an important turning point, came in the middle of this collapse. Jacques Kallis has carried all before him in the competition so far and came into this game averaging 314.00.
Yesterday, when he had made 15 in an innings that had already included a number of strokes that in-form batsmen go for and get away with, he played another firm-footed slash at Richard Johnson. He hit the ball in the air, but mighty hard. It flew at a great lick low to the ground to the right of Andrew Flintoff who was on his own at fourth slip.
Flintoff threw himself far to his right and somehow reached the ball when it seemed to be past him. He caught it between the first two fingers and the thumb. Fortunately for him he has big hands and long fingers and when he hit the ground - he was airborne when he caught the ball - he managed to hold on. If not a catch in a million, it was a catch in at least a couple of hundred thousand.
Kallis could not believe it and walked off as if sure that he had been the victim of an outrageous sleight of hand. He has looked unstoppable in England so far in spite of having to overcome personal problems with his father's health and the death of his uncle.
There is also a new, young captain in charge of South Africa's dressing room, which does not always suit the older, more experienced players.
But Kallis has been in the form of his life. Now, at last as far as England's bowlers are concerned, he has had a bit of bad luck. This could signal a turning point in his fortunes.
Just possibly the same will be true for Flintoff. He has always been a good slip catcher, even though this one prompted Mike Gatting to murmur things about Ian Botham who caught swallows in the same position.
Flintoff's crying need is for consistency, more than anything with the bat. Yesterday's powerful half-century again showed what he is capable of, even if he still seems to be uncertain of what is expected of him.