As if to add a further element of drama to this year's world title race, ahead of its fast-approaching finale on the North Shore...

Two separate shark attacks off the coast of Oahu yesterday left two men with serious injuries, little over a week after surfer Colin Cook lost his left leg on the North Shore.

The first attack took place near Lanikai beach on the island's east side, roughly 50 to 100 yards out to sea, when a 44-year old man was bitten on both his legs as he returned to shore from the nearby Mokolua Islands. The swimmer was helped to shore by his friend, who escaped unharmed, and several passing kayakers, before paramedics rushed him to hospital. The man was reportedly in a critical condition.

“We heard there was a shark attack so I ran over there to see if I could help," witness Dr. Brian Jones told to the Honolulu Star Advertiser. “At that point they were pulling him out of the water and you could see what the shark did. He was missing the bottom half of his left leg and the right leg was just barely hanging on."

The water was evacuated and nearby beaches closed by lifeguards.

The second attack occurred some seven hours later, just before 7pm, in waters off Waikiki beach on Oahu's south shore. A 32-year old man was bitten on his left foot by what is thought to have been a small shark, and according to city Emergency Medical Services was in a serious condition.

Waikiki beach in Honolulu