what does the standing leg mean？
Certainly, it was a clumsy finish and, looking back, I have to admit to being
embarrassed, but basically I was happy to take any goal, any time. Three seasons
later in Milan, I scored an even jammier one, with the ball going in off my standing
leg, but they all count. It was an ugly one – so what?

meaning supporting leg？

Question

what does the standing leg mean？
Certainly, it was a clumsy finish and, looking back, I have to admit to being
embarrassed, but basically I was happy to take any goal, any time. Three seasons
later in Milan, I scored an even jammier one, with the ball going in off my standing
leg, but they all count. It was an ugly one – so what?

meaning supporting leg？

Answer

It means that you had one leg in the air and one was still standing on the floor. So imagine this scenario:

You're stood facing the goal. The ball comes from the left, and you go to kick it with your left leg towards the goal. You swing at it with your left leg, but miss, and while your left leg it still in the air it hits your right leg and goes in.

The right leg would be called the 'standing leg'.