Carlsen-Ding MCI Semi-Final Game 1 : May 2, 2020 chess24.com

Here is the game featuring Magnus Carlsen versus Ding Liren, Magnus Online tournament semi-final Game 1. opening was the London  (d4, Bf4) which Carlsen plays quite a bit in rapid and blitz, for instance world blitz 2019 against Nakamura.

Here the position after 14..Nf6, White to play

The possibilities are 15 0-0-0 or 15 Qg2. Carlsen chose 15 a3!?

Here is where you can replay the full annotated game

https://share.chessbase.com/SharedGames/share/?p=HW3sNkHzg5/Fj9X9CMesvzBdmhgEziqNUqK8pqBZS/TR9wQ8ktaPnLNb7Mb81iI0