When Yasuo, Remorseful attacks a battlefield with a unit controlled by Nine-Tailed Fox's leader, in what order do their triggered abilities enter the chain?

According to Combat-initiated Showdown Initial Chain, triggered abilities are added to the chain in this order: first by the player with Focus (the Attacker), then by players without the Defender designation in turn order, and finally by the Defender. In this scenario, Yasuo's 'When I attack' ability enters the chain FIRST (since Yasuo's controller is the Attacker with Focus), then Nine-Tailed Fox's 'When an enemy unit attacks' ability enters the chain SECOND (since Nine-Tailed Fox's controller is the Defender). The general principle is: the active/attacking player adds their triggered abilities to the chain first, then the defending player adds theirs.