Google's AI AlphaGo just beat South Korean Go champion Lee Se-dol

In what's being hailed as a major milestone for artificial intelligence, a computer beat one of the world's top players of Go, an ancient Chinese board game which had previously remained one of the last great challenges for AI.

After about three and a half hours on Wednesday, Google's AlphaGo program defeated South Korean champion Lee Se-dol in a match Lee described as "hugely exciting" and "immensely tense." Until recently, Go has eluded the smarts of AI because the game requires high levels of intuition and evaluation. In October, however, AlphaGo became the first computer program to beat a professional Go player, by winning 5-0 against European champion Fan Hui.

The next four matches against Lee are scheduled for Thursday, Saturday and Sunday in Seoul, South Korea and will be livestreamed on YouTube. Lee is playing for a US $1 million prize. You can watch the last match just below.