SEOUL, South Korea * A champion Go player scored his first win over a Go-playing computer program on Sunday after losing three straight times in the ancient Chinese board game, saying he finally found weaknesses in the software.

Lee Sedol's victory over AlphaGo is a reminder that Google's Go- playing program has room for improvement despite winning the first three matches in the best-of-five series and the $1 million prize, which will be donated to charity. The program the first computer system to defeat a top Go player was developed by Google DeepMind two years ago.

"This one win is so valuable and I will not trade this for anything in the world," Lee, one of the best Go players in the world, said with a smile.

Lee had said earlier in the series, which began last week, that he was unable to beat AlphaGo because he could not find any weaknesses in the software's strategy. …