A paddle-wielding robot is so adept at playing table tennis that it is posing a tough challenge to elite human players and sometimes defeating them, according to a new study in the journal Nature that shows how advances in artificial intelligence are making robots more agile.

Ace isn't the first ping-pong playing robot. Researchers have long been interested in the sport because of its speed and real-time decision-making, which is a major frontier in robotics. In this respect, Ace marks a milestone for the AI system and for the highly reliable arm.