Swiss Super League side Basel and Bulgarian boys Ludogorets Razgrad -- a team that once held Liverpool to a draw -- are also in this pool .
Swiss Super League side Basel have proved problematic for Chelsea and Tottenham in Europe in recent years .
Swiss Super League side Basel , who have proved problematic for Chelsea and Tottenham in Europe in recent years , and Bulgarian boys Ludogorets Razgrad -- a team that once held Liverpool to a draw -- are also in this pool .