Korchnoi took the early lead, scoring 5/7 in the first cycle, ahead of Petrosian, Geller and Keres with 4 points. But in the twelfth round, Korchnoi blundered against Fischer in a winning position and lost, and soon after lost four games in a row. The tournament became a three-way race between Petrosian, Keres and Geller. After three full cycles (21 rounds), Keres led on 14½, narrowly ahead of Petrosian and Geller on 14, with the others out of contention (Korchnoi 11, Fischer 10, Benko 9, Tal 7, Filip 4½).