Before this play… No, even far before that, Riku noticed that he had been stared at constantly by Sawada from the other side of the net. At first, he thought the boy was just targeting Yuki. But after a while, he realized he was also under Sawada's radar.
He also knew that even though they had little to no contact before this game, Sawada had already known about his overly high competitive spirit. It was something that he could never conceal.
So, adding those two facts, together, Riku laid a careful plan to lure Sawada out to the front line and expose his weak defense.
Riku deliberately raised his voice when he said he wanted to stabilize the game first so that Sawada could hear and guess his plan. With his sharp instinct, there was no way Sawada wouldn't guess it was just a fake call and he would do the same dump attack just like Sawada did before.
However, that was the bait that Riku sent to lure him out.
