Groups stage match generator

Question

so im trying to create sort of "match generator" in TypeScript for All-In-All tournament type (i guess its called like that).

class Player {
    id!: number
    username!: string
    points!: number
    group!: string
}

class Match {
    players: Player[] = []
    scores: number[] = []
}

let players: Player[] = [];

for (let i = 1; i < 6; i++) {
    let player = new Player();
    player.id = i;
    player.username = 'random' + i.toString();
    player.points = 0;

    players.push(player);
}

function test(n: number) {
    for (let i = 0; i < n - 1; i++) {
        console.log("Round" + i + 1);

        for (let j = 0; j < n / 2; j++){
            console.log(players[j].username + "VS" + players[players.length - 1 - j].username)
        }

        players.splice(1,0,players[4]);
        players.pop();
    }
}

console.log(test(players.length));

But for some reason im always getting matches pairs which i shouldn't.'

Test output :

[LOG]: "Round01" 
[LOG]: "random1VSrandom5" 
[LOG]: "random2VSrandom4" 
[LOG]: "random3VSrandom3" 
[LOG]: "Round11" 
[LOG]: "random1VSrandom4" 
[LOG]: "random5VSrandom3" 
[LOG]: "random2VSrandom2" 
[LOG]: "Round21" 
[LOG]: "random1VSrandom3" 
[LOG]: "random4VSrandom2" 
[LOG]: "random5VSrandom5" 
[LOG]: "Round31" 
[LOG]: "random1VSrandom2" 
[LOG]: "random3VSrandom5" 
[LOG]: "random4VSrandom4" 
[LOG]: undefined 

I believe i just forgot or missed something , anyone could lead to a direction ?

Thanks in advance.