 Complete the following phrase:  It gained popularity after Ernst Grünfeld introduced it into international play at Vienna 1922, where, in his first game with the defense, he defeated future world champion Alexander Alekhine. Grünfeld usually employed a very classical style. The defence was later adopted by a number of prominent players, including Vasily Smyslov, Viktor Korchnoi, Leonid Stein, and Bobby Fischer. Garry Kasparov often used the defence, including in his World Championship matches against Anatoly Karpov in 1986, 1987 and 1990, and Vladimir Kramnik in 2000. Currently active notable players who employ the opening include Maxime Vachier-Lagrave, Loek van Wely, Peter Svidler, Peter Leko, Viswanathan Ad, Luke McShane and Gata Kamsky. Ad employed it twice in the 