MITO, Japan - The chance of yokozuna Hoshoryu taking part in the Autumn Grand Sumo Tournament in September is in doubt after he underwent right knee surgery in late July, his stablemaster said Thursday.

Hoshoryu is yet to win an Emperor's Cup in nine meets since earning promotion to yokozuna ahead of the Spring meet in March last year. The Mongolian-born grand champion has pulled out during a tournament four times in that period, including the last two.

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