Players joining a new Saudi-backed golf series will face disciplinary action, the PGA Tour warned on Wednesday in the wake of Dustin Johnson’s shock decision to join the money-spinning new venture. In a brief statement, the PGA Tour said that any player participating in events on the LIV Golf Invitational Series without authorisation would be subject to sanctions. On Tuesday, former world number one Johnson was named on a list of 42 players who will take part in the lucrative LIV series’ opening event outside London next week, which clashes with the PGA Tour’s RBC Canadian Open in Toronto. “As…