MONTREAL (AP) _ Hockey great Maurice ``Rocket'' Richard slipped into a deep coma overnight and doctors say it's impossible to tell how much longer he has to live.

The former Montreal Canadiens star, fighting abdominal cancer, had a significant drop in his blood pressure and had trouble breathing overnight, according to a statement released by the Hotel Dieu hospital this morning.

On Friday, doctors found that Richard's spinal column was deteriorating due to osteoarthritis. The osteoarthritis was also causing pain in the hockey legend's legs.

The 78-year-old was admitted to hospital last week after the recurrence of a cancerous abdominal tumor that first appeared three years ago.

Chemotherapy has been mentioned as an option but only if Richard regains enough strength to endure the treatments.

Richard became the NHL's first 50-goal scorer in 1944-45 and went on to score a then-record 544 in his career with the Canadiens. He also scored 82 playoff goals and won eight Stanley Cups.