Eleven-time TT winner Phillip McCallen says he expects "fireworks" when Ian Hutchinson and Michael Dunlop go head-to-head in Friday's six-lap Senior TT.
The pair have dominated this year's meeting on the Isle of Man throughout practice and race week.
The rivals face a high-speed finale in the blue riband event of the festival with both in record-breaking form.
"The fact they're both riding BMW bikes for different teams gives the whole thing added spice," McCallen said.
Spectacular speeds on the Mountain course
Dunlop raised the absolute lap record for the circuit to 133.39mph and Hutchinson went through the 132mph barrier in setting a new benchmark for the Superstock class.
"Michael stamped his authority by winning the Superbike race and you would have expected Ian to maybe be psychologically damaged by that, but he has responded by winning the next three races and the pendulum has swung in his favour again," said McCallen.
"They have been the fastest men on track in every race and I'm not surprised by the high speeds and the fact Michael set the first sub-17 minute lap, because they are good bikes ridden by very good rider.
"I believe the lap record will go even higher on Friday as both guys will be feeling confident, although there will be some pressure there too."
Both riders will be aiming to add to the solitary Senior successes they have enjoyed in their careers to date and McCallen is reluctant to predict who will come out on top after the 226-mile race.
"It is years since we have had this kind of build-up to a Senior TT - it's going to be close and I'm not sure which one is going to win.
"They are two very different personalities with different approaches - Michael is so determined and fiercely competitive, while Ian is professional, slick and organised.
"There are differences between them in that one is very much into corporate presentation while the other is a more humble set-up but one thing is for sure, the two riders are both fast."
Yorkshireman Hutchinson, 36, who has now joined the legendary Mike Hailwood on 14 wins and 27-year-old Northern Irishman Dunlop, with 12 victories to his name, have set the pace all week.
McCallen expects that to continue, despite John McGuinness being in the field.
The 23-time winner pulled something of a rabbit out of the hat in winning the Senior races in 2013 and 2015, having been written off by many observers on both occasions.
"John is a wonderful rider and I'm not saying he hasn't the ability to go at the same pace as those guys but I feel the bar has been raised that little bit too high for him.
"Nobody has been in the same league as Ian and Michael this week and to push on that extra mile per hour every lap to match those two is maybe more than he wants to do at this stage of his career."