Part of the fun of the Grenke Chess Classic is that it features the first game between Fabiano Caruana and Magnus Carlsen, now that the former is the official challenger for the latter's world championship title. And we didn't have to wait: they were paired for round 1, and that game is underway now.
The other pairings are: Viswanathan Anand - Hou Yifan, Georg Meier - Levon Aronian, Arkadij Naiditsch - Maxime Vachier-Lagrave, and Matthias Bluebaum - Nikita Vitiugov.