St Louis (USA): Indian chess grandmaster Koneru Humpy inflicted a defeat on Valentina Gunina of Russia in the eighth round of the second Cairns Cup here, jumping into sole lead with 5.5 points and a round to play.
In a huge upset, 16-year old America Carissa Yip stunned world champion Wenjun Ju in a 61-move game late on Saturday, taking her tally to 3.5 points.
Dronvalli Harika, the other Indian in the field, was held to a third consecutive draw by former world champion Mariya Muzychuk. She now has four points and is joint fifth with Katernya Lagno.
Interestingly, Humpy will meet Harika in the final round with the former in with a chance to claim the top prize.
In the Humpy-Gunina game, the Indian opted for Semi-Slav and outplayed her rival in 35 moves to record her fourth win of the tournament.
In the Yip-Ju encounter, the young American attacked on both flanks to surprise the Chinese star. Yip had started with four straight defeats and has now bounced back in style with three wins.
Russia's Alexandra Kosteniuk, a former world champion, is hot on the heels of Humpy, with five points, after posting a win over Nana Dzagnidze.
In the day's other game, local star Irina Krush played out a draw against Lagno.
Results: Round 8: Carissa Yip (USA) 3.5 beat Wenjun Ju (China) 4.5; Koneru Humpy (India) 5.5 beat Valentina Gunina (Russia) 2; Mariya Muzychuk (Ukraine) 4.5 drew Dronavalli Harika (India) 4; Nana Dzagnidze (Georgia) 4 lost to Alexandra Kosteniuk (Russia) 5; Katernya Lagno (Russia) 4 drew with Irina Krush (USA) 3.