Which 3 mens tennis players have the most grand slam singles championships?
Novak Djokovic, Rafael Nadal, and Roger Federer have the most grand slam singles championships.
<START_INST>Which 3 mens tennis players have the most grand slam singles championships?<END_INST><START_CTX><END_CTX><START_A>Novak Djokovic, Rafael Nadal, and Roger Federer have the most grand slam singles championships.<END_A>