Chess (#1167)

The World Cup quarterfinals are on. At the time of writing, Anish Giri and Pavel Eljanov have qualified for the semis, beating Maxime Vachier Lagrave and Hikaru Nakamura, respectively. Peter Svidler and Wei Yi battle it out in one tiebreaker and Shakhriyar Mamedaryov and Sergei Karjakin are in another tiebreaker.

The big guns have mostly been knocked out. The #1 seed, Veselin Topalov lost to Peter Svidler. #9 Levon Aronian was knocked out by #56 Alexander Areshchenko, while #3 Fabiaono Caruana went down to #19 Shakhriyar Mamedaryov. The #2 seed, Hikaru Nakamura survived on technicality against Ian Nepomniachtchi after committing an offence, before he lost to #26 Pavel Eljanov, who also beat #7 Alexander Grischuk.

The Ukrainian GM, Eljanov, started with three successive maximum 2-0 wins, and then he took out Dmitry Dmitry Jakovenko and Nakamura.

But the star has been 16-year-old, #24 seeded, Wei. He has won a couple of desperate tiebreakers, including a big win against compatriot and world #8, Ding Liren.

Giri, seeded #4, is the highest rated player in the fray. The Dutchman has now played 40-odd classical games on the trot without a loss. He's had a hard roster in Alexander Motylev, Peter Leko, Radek Wojtascek and Vachier Lagrave, and never looked in serious trouble. Giri meets Eljanov in the semis.

Mamedaryov and Svidler are sharp players who rely on tactical skills and their ability to create unbalanced positions. Giri and Eljanov are both solid stylists. Karjakin is universal, capable of playing either sharp or solid. Wei is still an unknown quantity in many ways. He has great tactical skills, he's fearless and has good nerves. But he's too young (and developing too fast!) for any clear picture of possible weaknesses.

As always in a World Cup, quality has varied between the excellent and the comical, with some splendid games and also some terrible errors. In the DIAGRAM, WHITE TO PLAY (White: Eljanov Vs Black: Nakamura, World Cup 2015 Baku), Eljanov displays great technique until he misses checkmate.

First, a neat pawn sac. 40.Ra2! Rxd4 41 Rc2 Na8 42.Ra6 Rd1 43.h4! h5 44.Ke3. White has tied down black's pieces and breaks in via the dark squares. (The 43 h4 thrust threatened h5 with structural paralysis.)

Play continued 44...Rg1 45.Kf4 Rg2 46.Rd6 Rg1 47.Rc8 Ra1. The next pawn sac is clearer than 48. Rxd5 which also wins. White played 48.Kg5! Rxa7 49.Rdd8 g6 50.Rh8+ 49.Rdd8 g6 50.Rh8+(?) Missing 50.Kf6 Kh6 51.Rh8+ Rh7 52.Rcg8 and checkmate but after 50...Kg7 51.Rcg8+ Kf7 52.Rxg6 Ra6 53.Rh7+ Kf8 54.Kxh5 Nb6 55.Kg5 Nc4 56.h5 Nd6 57.Rf6+ Kg8 58.Rd7 (1-0).

Devangshu Datta is an internationally rated chess and correspondence chess player