With a final score of 3½-1½, and with a game to spare, Lei Tingjie defeated Tan Zhongyi in the Women's Candidates Final and will now challenge Ju Wenjun in the upcoming Women's World Championship match, scheduled for July in Shanghai and Chongqing.
In a must-win situation - a draw would leave Lei Tingjie with the white pieces in the last round with draw odds - Tan Zhongyi whipped out the Colle-Zukertort system, a rare bird in top-level events, but extremely popular at the club level.
According to my database, in more than 600 official tournament games playing White, Tan Zhongyi has never employed this variation before: a risky choice for such an important game.
The surprise effect didn't work out. Lei Tingjie reacted fast, demonstrating splendid match-play opening preparation. She uncorked a novel idea (7…g6!?), delaying castling in favour of a dangerous kingside pawn avalanche. Although the line has been tried out on a few occasions by +2500 grandmasters in the past (notably Lopez Martinez and Cornette), it's clearly not mainstream.
By move 14, Black had already taken over the imitative on the kingside. Although the engines were still offering an equal evaluation, and the situation on the clock was also similar, it did feel that Lei Tingjie was playing aggressively to end the match here and now.
The key moment of the game came unexpectedly. Under certain pressure on her castled king, Tan Zhongyi played 21.g3? breaking the golden rule of not moving the pawns in front of your king unnecessarily. Lei Tingjie's masterful reply 21…Nd8!! highlighted immediately White's new weaknesses in her castled king position. The maneuver Nd8-f7-g5-f3 would prove to be decisive.
In the commentary booth, GM Alik Gershon was bowled over: "Wow! Look what Lei did: 21...Nd8! This is extremely impressive! She reacts immediately to 21.g3, which has a very serious drawback - it weakens the f3 square."
From then on, it was plain sailing for the new Women's World Champion contender. All of Black's pieces surrounded White's king, and after 33…Rxg4 the attack crashed through and it was all over for Tan Zhongyi. A fine attacking game by Lei Tingjie that topped off her dominant performance in the match.