Kasparov Variation 4.Nf3
| a | b | c | d | e | f | g | h | ||
| 8 | 8 | ||||||||
| 7 | 7 | ||||||||
| 6 | 6 | ||||||||
| 5 | 5 | ||||||||
| 4 | 4 | ||||||||
| 3 | 3 | ||||||||
| 2 | 2 | ||||||||
| 1 | 1 | ||||||||
| a | b | c | d | e | f | g | h |
4.Nf3 is known as the Kasparov Variation, since Garry Kasparov used it to great effect against Anatoly Karpov in their 1985 World Championship match. Kasparov played 4.Nf3 six times, scoring three wins and three draws. Today as White, this is a favourite weapon of GM Alexei Barsov and former Women's Champion Nona Gaprindashvili.
White develops the knight to a natural square and waits to see Black's reply. 4...d5 transposes to the Ragozin Defence of the Queen's Gambit Declined and 4...b6 5.Bg5 Bb7 transposes to the Nimzo/Queen's Indian hybrid line, so 4...c5 is the most common move that stays within Nimzo-Indian territory. Now 5.e3 transposes to the Rubinstein System, but the main move is 5.g3, which leads to a position that also arises from the Fianchetto Variation. 5.g3 cxd4 6.Nxd4 0-0 7.Bg2 d5 8.cxd5 Nxd5 can be considered the main line. Black has dissolved White's centre, but the bishop on g2 exerts pressure on the black queenside, which White may augment with 9.Qb3.
This line can also arise from the Bogo-Indian Defence (1.d4 Nf6 2.c4 e6 3.Nf3 Bb4+) if White blocks the check with 4.Nc3. Most Bogo-Indian players are also Nimzo-Indian players, but for those who are not, this transposition into the Nimzo is something they need to be prepared for.
Read more about this topic: Nimzo-Indian Defence