The Airlie Birds’ impressive progress was slowed with last Thursday’s disappointing 18-10 loss at bottom-placed derby rivals Hull KR.
Moreover, just 24 hours later, Saints staged a stunning fightback in the last quarter to win 21-10 at second-placed Warrington Wolves.
That extended their lead at the top to eight points and Radford conceded: “To date, they’ve been the best team in the competition.
“They’re playing a great brand of rugby and for us to get them Friday, then we’re going to have to be at our best.
“I watched Saints against Warrington; I just thought the level of intensity in that game was raised.
“It had the play-off feel about it with the contact and speed of the game. I’m anticipating this game to be exactly the same. They came out on top against a very strong Warrington side.
“I’ve spoken to the players and said these are the fixtures that you want to play in.”
Hull were missing talisman stand-off Albert Kelly in the derby but he should return tonight as should another totemic player – Gareth Ellis.
It means Radford will be able to field arguably his strongest side for more than a year.
“We’ll find out a lot about ourselves in this game and for that reason it’s one I’m looking forward to,” he added.
“What I’ve said from day dot is that when we’ve got our best team on the field then we can compete with any team in the competition.”
Asked where Saints have set themselves apart – Justin Holbrook’s team have won 18 of 20 league games – Radford said: “I’d say the level of execution is the main difference between them and a few other sides.”
Execution is something which let third-placed Hull down at prime times in the derby but the return of Kelly, which will allow Jake Connor to switch to centre, should help solve that problem.
Saints could be vulnerable, too, given they go into the game with no recognised hooker. James Roby is out and Aaron Smith was stretchered off against Warrington.
Meanwhile, in-form winger Ratu Naulago – who only arrived on trial from the British Army in the off-season – has seen his contract extended by Hull until the end of 2020 after scoring 10 tries in 13 games.