Sadler has been very solid, beating Michael Adams but drawing all the rest of his games. Despite his fine rating of 2,660, Matthew is still establishing himself among the world's best players with relatively little experience in top-class tournaments. He lost a large number of games at the Amber Quickplay and Blindfold Quickplay tournaments in Monaco in March (as in the note about Kramnik vs Van Wely, below): so his impermeability in Tilburg is no bad thing. Meanwhile Michael Adams had been rather more up and down, also losing to Anand but beating Svidler and Korchnoi.
Unless you stick to a rigidly defined repertoire, the choice of an opening as Black against a player as talented and erudite as Viswanathan Anand always has some element of Russian roulette. On Saturday, Korchnoi spun the barrel most unpropitiously and was dispatched in just 19 moves and 75 minutes. After the game he complained "Why did I play this horrible variation... I know so much theory after 1 d4 and yet I went for this ridiculous variation I have never played before. I lost without a fight."
In fact the line has often been favoured by Michael Adams. Black keeps a good pawn structure but at the cost of some development. Korchnoi characterised 9 a3 as "cowardly" but in his preparation he had missed the blindfold game between Kramnik and Van Wely in Monaco - a tournament Anand was present at. Van Wely was also caught by 15 Bd1. His 15... a6 was comparatively better, but he duly lost in 46 moves.
After 15... b5? the bishop on b3 was in trouble. 17... e5 was desperate, but if 17... Be7 18 Nd2 Bc4 19 Nxc4 bxc4 and perhaps 20 Bxa7 first (rather than 20 Rxc4) White would surely win. In the final position 19... Ra8 20 Nd4 Be6 21 Nxe6 fxe6 22 Rc7 is absolutely hopeless.
White: Viswanathan Anand
Black: Victor Korchnoi
Queen's Gambit Semi Tarrasch