I remember some other keeper saying he judged both the poise/angle of the penalty taker (as geysir mentioned above) and the distance between the penalty taker's 'non-kicking' leg and the ball as he planted it before actually kicking the ball. The closer it was to the ball, the more likely the penalty taker was to sidefoot it to the keeper's left (if the penalty taker was right-footed). The farther away it was planted from the ball, the more likely he was to put it to the keeper's right. If the kicker's left arm moved away from his body for balance, that was another sign he would put it to the keeper's right.
Steven Gerrard is one who used to do this - look like he was going to smash it in the run-up and then open up his body and place it to the keeper's left.
I've asked on foot.ie before about just how much of 'send the keeper the wrong way' is real and how much is nonsense, but when you see some of the penalties from that shootout (Griezmann in particular), you have to wonder - to hit it so far from the corner, they'd need to be very confident that the keeper would go the other way (or that they had delayed it just enough to see him go the other way). Either way, balls of steel.
