Though the Intellivision was not the first system to challenge Warner Communications's Atari, it was the first to pose a serious threat to the market leader. A series of advertisements featuring George Plimpton were produced that demonstrated the superiority of the Intellivision's graphics and sound to those of the Atari 2600, using side-by-side game comparisons. One of the slogans of the television advertisements stated that Intellivision was "the closest thing to the real thing"; one example in an advertisement compared golf games. The other console's games had a blip sound and cruder graphics, while the Intellivision featured a realistic swing sound and striking of the ball, and graphics that suggested a more 3D look. There was also an advertisement comparing the Atari 2600 to it, featuring the slogan "I didn't know". In its first year, Mattel sold out its initial 175,000 production run of Intellivision "Master Components". In 1981, over one million Intellivision consoles were sold, five times as many as in 1980.