Has Conor McGregor's market appeal suffered a knock-out blow?

Guru warns punch-ups will hurt MMA star

Controversy: Conor McGregor reacts after losing to Khabib Nurmagomedov in his last UFC fight in Las Vegas in October 2018. Photo: AP

Ralph Riegel

One of the world's leading sports marketing experts has warned that Conor McGregor's latest controversy could herald the beginning of the end for the fighter's commercial appeal.