SEOUL, South Korea — Ending what was billed as the match of the century, a Google[1] computer program defeated a South Korean master of Go, an ancient board game renowned for its complexity, in their last face-off on Tuesday.

The program AlphaGo's 4-1 victory was a historic stride for computer programmers and artificial intelligence researchers trying to create software that can outwit humans in board games.

"It made me question human creativity. When I saw AlphaGo's moves, I wondered whether the Go moves I have known were the right ones," the human competitor, Lee Se-dol, 33, said during a postmatch news conference. "Its style was different, and it was such an unusual experience that it took time for me to adjust."

"AlphaGo made me realize that I must study Go more," said Mr. Lee, one of the world's most accomplished players.

Go is a two-person game of strategy said to have been created in China more than 3,000 years ago. The players compete for territory by placing black and white stones on intersections of a board of 19 horizontal and 19 vertical lines.

The game has been the last remaining great hurdle for computer programmers attempting to make software more adept than humans at board games since the I.B.M.-developed supercomputer Deep Blue routed the world chess champion Garry Kasparov in 1997.

Artificial intelligence experts had predicted that a computer program needed at least 10 more years of development before it would be able to beat Go masters like Mr. Lee.

But AlphaGo, created by Google's artificial intelligence company DeepMind, had already surprised the Go community when it trounced the three-time European Go champion Fan Hui in October, 5-0. It then challenged Mr. Lee, a far stronger opponent with 18 international titles under his belt.

AlphaGo quickly decided the best-of-five series, winning the first three matches. (Google has said it plans to donate the $1 million prize to Unicef and other charities.)

But Mr. Lee staged a dramatic comeback and demonstrated a human resilience on Sunday, when he defeated AlphaGo in the fourth game.

Millions of Go fans in Northeast Asia, where the game is especially popular, watched intently during the match on Tuesday. It lasted the longest of the series: five hours.

Although many viewers did not understand the intricate play, the tension was clearly acute toward the end of the game. Each player was given one minute to deliberate and foresee complex moves and countermoves before placing a stone.

During a postmatch ceremony, Hong Seok-hyun, head of the Korean national Go association, awarded the AlphaGo team the certificate of an honorary Go degree of Nine Dan, the highest granted. Mr. Lee also holds that degree.

Demis Hassabis, the chief executive of Google DeepMind, said playing Mr. Lee had exposed several weaknesses of AlphaGo that his team would try to address. Computer algorithms used for AlphaGo "one day can be used in all sorts of problems, from health care to science," he said.

More than 100 million people had watched the AlphaGo-Lee matches, Mr. Hassabis said. He said he hoped that the attention would encourage more people to learn Go, the "most profound game humankind has devised."

Mr. Lee said AlphaGo was unlike any human opponent he had faced.

"It remained unfazed psychologically and stayed focused," he said. "In that regard, I don't think humans can beat it, even though I hesitate to admit that AlphaGo is above humans in Go skills yet."

Until the matches with AlphaGo, Mr. Lee said he had begun wondering whether he was enjoying the game anymore. But he said the games had renewed his enthusiasm for Go, which he began playing professionally at age 12.

"I have some regrets about the matches I have played against AlphaGo," he said. "But I could not have enjoyed them more."

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