The injured man was helping deliver a hot tub into the garden of a house, when the ground underneath the crane appeared to give way.
The crane also crashed into the roof of a nearby house where an elderly couple were inside.
The woman who lives in the house was in an upstairs bathroom when she heard a loud bang as the crane crashed into her roof.
Paul Whitby, who was having the hot tub delivered, told Thisisnottingham: “I thought the tub had landed in their conservatory at first, so I thought ‘My God’, because they spend most of their time in there. It was a scary moment.
“I had just gone in the kitchen and heard a shout and a crash and came running out.”
The incident happened in Stoke Lane, Gedling, at about 1.45pm yesterday. The crane was situated behind a derelict bungalow which is due to be demolished next week.
Electrician Gregg Titmuss helped pull the man free while waiting to wire the hot tub in.
He said: “I heard a commotion. I saw the tub coming down rather rapidly. It landed. I spotted Richie stuck between the derelict bungalow and the crane.
“He was conscious and talking. I dragged him out and we rang the ambulance and pulled him further away and kept him conscious and talking with us.”
The injured man, aged 20 and known as Richie, was taken to hospital with serious but not life-threatening abdominal and pelvic injuries.
A structural engineer visited the elderly couple’s house to check the damage. The Health and Safety Executive also visited the site to investigate the incident.