Great Tigran’s heir

Tigran Petrosian is the great chess hero of Armenia. World champion from 1963-1969, his best games exhibit a profundity which few other champions have matched. Sadly he passed away in his fifties, in 1984, but his legacy lives on in Levon Aronian, who has emerged victorious from Stavanger. Scores from Norway (out of 9) were Aronian 6; Nakamura and Kramnik 5; Caruana, So and Giri 4½; Vachier-Lagrave, Anand and Carlsen 4; Karjakin 3½.
 
Aronian-Kramnik: Stavanger 2017
(diagram 1)
 
Here Black should play 19 … Qg5. 19 … Qg4 20 g3 Now White has weaknesses along the h1-a8 diagonal but his central pressure more than outweighs this. 20 … fxe5 21 Qxe5 Rcd8 This is far too passive and now Black is lost. He had to try 21 … Kh8, meeting 22 f4 with 22 … Nd7 with chances to resist. 22 f4 Rf6 23 Rc3 Rh6 24 Be2 Surprisingly, Aronian misses 24 Nf5 winning at once.