Marian Vajda was Novak Djokovic's coach.

After retiring from tennis, he became captain of both Davis' and Slovakia's Fed Cup teams. In June 2006 he became Novak Dokovic's coach, helping to bring him to the top of world tennis. In 2013 Djokovic's new head coach became Boris Becker, but Vajda remained on the staff until 2017, when new coaches Andre Agassi and Radek Stepanek arrived. In 2018 Djokovic terminated the contract with Agassi and Stepanek and recalled Vajda as head coach.

The Serbian champion had just returned from a serious injury and a long crisis of results. Vajda persuaded him to abandon the vegan diet and to alienate the spiritual guide Pepe Imaz.

The relationship with Djokovic broke down again in March 2022, and in May the announcement came that he would become the new technical guide of the emerging compatriot Alex Molcan, Slovakian No. 1.