Issues 25 and 26. IMHO, one of the best story lines in comics. What I liked about Marvel was they were never shy about having a stronger character take on a weaker character. If Namor appeared in Daredevil - which he did - Namor would kick his butt - which he did. The same with these two issues. The Hulk discovers Rick Jones left him for Captain America and becomes super-pissed. He takes off for NYC and commences to tear the city apart. The Avengers are out of town, looking for him in the desert. The FF take him on. However, Mr. Fantastic is sick and bed-ridden. The Hulk breaks the Torches arm. The Invisible Girl passes out due to the incredible stress the Hulk places on her force fields. And the Thing is finally beaten by someone as he gets a wake up call like you could not imagine. Thinking he was always all powerful, he comes across an enraged Hulk who gets stronger and stronger as he gets madder. He beats the Thing into the pavement. The Avengers make an appearance and pretty much get beaten too. A great two issues as both the FF and the Avengers realize what the Hulk is capable of doing. Jack Kirby's art was fantastic - to say the least.
Exactly how I remember it!