There aren't too many people in the world who have shared the ring with Joseph Parker and Anthony Joshua.
Both heavyweight champions ended up in the win column against Carlos Takam, although they struggled at times against the diminutive but powerful Frenchman.
Parker was on the right side of a decision two-years ago while Joshua stopped Takam inside 10 rounds last year.
But you don't have to look too far to find one other person who has been up close and personal with the two undefeated sluggers.
Junior Fa, undefeated himself in the professional ranks, fought Parker on two occasions as an amateur and has been a training partner of Joshua in his past camps.
The 14-0 heavyweight told Newshub that he has never felt power like that possessed by the Brit, but he believes the Kiwi's speed could be a deciding factor on Sunday in Cardiff, particularly if Parker throws combinations.
"Combinations you know .. a fast combination puncher is always hard to deal with.
"Anthony Joshua is a very great counter puncher. One punch.
"Parker doesn't do that you know. Parker likes to throw his punches in bunches which is very hard to counter off," he told Newshub.
Fa is picking the Kiwi fighter to win, which he says is down to his better conditioning. But he says it will be a tough fight.
"I can see this going four ways. I can see both of them knocking eachother out and both winning by points.
"But I'm favouring Joseph Parker. We have seen Joshua fade in the later rounds. If Parker can put on a good pace, keep Joshua running for the first few rounds, which will get his legs tired, then mid-rounds get him stuck in the mud.
"Land a big punch and land a few combinations that will drop him."
Watch the video above for the full Newshub story.