The Avengers # 69 - Let The Game Begin

A small figurine turns out to be the Growing Man and scoops up a wounded Tony Stark and escapes. The Avengers attempt to stop the strange stimuloid, but are powerless against his ability to grow upon impact. Instead they follow him as he returns to Kang's future. Once there they discover that this was all part of Kang's plan and now the Avengers must help Kang in a game against the Grandmaster. Should they lose, the Earth will be erased out of existence. Teleported away, they quickly encounter their opponents...The Squadron Sinister!

Fuller Synopsis for "Let The Game Begin"

The Avengers have made a special visit to Tony Stark, who is in the hospital near death (Following the events of Iron Man #19) they are soon joined by fellow Avengers, Captain America and Thor. During their visit, the Wap comes across a tiny figurine, which is actually one of Kang's Growing Men. The creature grows in size and battles the Avengers, capturing Tony Stark and transporting all involved away to a distant place. They soon find themselves in the 4000 A.D. throne room of Kang the Conquerer.
After a brief battle against Kang's guards, the Avengers are informed that Kang has enlisted their aid in helping him best a cosmic being known as the Grandmaster. Kang explains that he was visited by the Grandmaster who offers him the opportunity to restore his comatose lover, Ravonna, if he were to win a "chess" game which pits champions of Kang's choosing against those selected by the Grandmaster. However, should Kang loose, not only will Ravonna not be awakened, but the whole universe would be doomed to oblivion.
The Avengers agree to helping Kang, on the condition that Tony Stark is returned to Earth, upon Star's return the Grandmaster appears and selects Captain America, Goliath and Thor, who are to be joined by a fourth comrade on Earth to battle his champions: Hyperion, Nighthawk, Dr. Spectrum and the Whizzer.