In conjunction with Juggernaut reappearing in comics in Amazing Spider-Man 627, Marvel is allowing free reading for the classic here.
The Story very much summarized
Amazing Spider-Man 229
The story opens with someone narrating a dream in Biblical language about the 'Dark One' fighting the Spidery Champion. In the dream, the Dark one defeats the Spidery champion and brings chaos.
Madame Web has the power to see the future. Obviously she saw herself being killed. And only Spidey can save her. Back in real life Madame Web contacts Peter asking for help.
Peter, as Spidey tries for a very long time to stop Juggernaut as he makes his way to kidnap Madame Web as ordered to. Clearly in this issue Spider-Man has never met Juggernaut. He makes his way to Dr Strange to find help. Although Strange is not in, Mr Wong helps, and Spider-Man is able to learn that Juggernaut had some past dealings with the X-Men, who are now too far to help.
Left with no help, Spider-Man goes to Madame Web's apartment before the Juggernaut does. The story ends just like in Madame Web's dream - with Spider-Man dodging all Juggernaut's blows until the ceiling collapses. Juggernaut, unknowingly yanks Madame Web from her life support system. Thinking she is dead, Juggernaut leaves disappointed.
Spider-Man recovers later and decides to continue hunting the Juggernaut.
Amazing Spider-Man 230
The story continues as Spider-Man chases after Juggernaut. When he finally meets him, he tries to catapult a few bars of metal at Juggernaut, only to find himself face to face with his foe again.
Spider-Man finally tosses a 3 ton steel ball at him, which is easily deflected into a building that falls on both Spider-Man and Juggernaut. Spider-Man luckily was able to take shelter under a some reinforced sewer pipes.
When Spidey gets out, learns that Juggernaut easily walked out of the rubble as well. Back at square one, Spider-Man looks for Juggernaut again. With another genius idea, Spider-Man decides to crash into Juggernaut with a fuel tanker - which obviously doesn't work. Spider-Man finally decides to cover Juggernaut's eyes while withstanding constant pounding on his back. Strangely enough, being unable to see, Juggernaut walks into some wet cement, which happens to be the foundation for a high rise building.
Peter later goes to the hospital to visit Madame Web only to find out that she has lost her memory and paranormal abilities.