Probleme erreur SQL

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE pseudo="test"' at line 1

if(isset($_POST['pseudo']))
{
$sql2 = 'SELECT COUNT(*) AS nbr WHERE pseudo="'.mysql_real_escape_string($_POST['pseudo']).'"';
$query2 = mysql_query($sql2) or exit(mysql_error());
$donnees2 = mysql_fetch_assoc($query2);
}