How to populate a single tournament elimination randomly in PHP without repeat?

If i have this:

$players = array("A","B","C","D","E","F","G","H","I","J","L","M","N","O","P","Q");

How i populate a single tournament elimination like this for example:

Matche 1: AxL
Matche 2: CxJ
Matche 3: HxQ
.
.
.
Matche 8: ExP

16 players = 8 Matches