"Every minute that goes by they're edging closer and closer to each other," he said.
"When we see it eventually arriving up the Derwent River we're going to have a battle on our hands."
Wild Oats XI is vying for her record eighth line honours in the race and short of an equipment failure or lack of wind, remains well placed.
However the forecast patchy winds around Tasman Island where the yachts turn into the Derwent River, could prove problematic for the leader.
"It is still possible that Wild Oats XI could sail into a windless patch of water, leaving Comanche to sail around her," race organisers said in a statement.
Kimo admitted the Derwent can be tricky.
"The whole thing is wide open ... I hope we get a little lucky," he said.
Anything can happen in the closing stages of the race and it's essential for Wild Oats XI to keep its lead over Comanche if she is to go on to victory, Cameron said.
"Going up the Derwent as the breeze lightens, the conditions are changing, you've got current, you've got wind," he warned of the unpredictable entrance to Hobart.
Behind the leading pair, American boat Rio 100 has moved into the hotly contested third place, 153 nautical miles from the race leader.
She is joined by Tasmanian yacht Alive, Ragamuffin 100 and Ichi Ban who are all close to the front of the main race pack which continues to move across Bass Strait.
During his four-decade association with the race Cameron has never seen such congestion.
"I can't recall seeing a compressed situation (like) in this case," he said.
"At this point in time we have nearly every boat in Bass Strait."
NSW 32-footer Quikpoint Azzurro leads the early front runners for handicap honours, with the final result possibly not due until Tuesday.
"We're going to find that the overall winner is going to change 20 or 30 times before we get a final result," Cameron said.
Meanwhile, Perpetual LOYAL arrived at Rose Bay in Sydney on Sunday morning after being forced to retire from the race after suffering damage to the front of her hull.
- AAP
