The tie of the round, pitting the holders against the reigning Super League champions, is televised live on the BBC this afternoon.
Given Long’s rich history with Saints, it is understandable why his involvement has caught the eye.
The former Great Britain scrum-half won the Challenge Cup five times with them and remains the only player to claim the Lance Todd Trophy as man-of-the-match on three separate occasions. Long was also assistant coach with Saints before briefly switching to union with Harlequins in 2019 and faces them for the first time since joining Leeds.
But Agar – whose injury-hit side have started Super League with a win against Wakefield Trinity and defeat versus Castleford Tigers – insisted: “I don’t think the Saints connection has been too much part of our build-up.
“Clearly, Sean knows some of their players and what plays they prefer and what plays they don’t, but we will be concentrating on ourselves a little bit more.
“It is important we try and get our own jobs right. Over (Super League) rounds one and two we have seen it at times, but we would like to be a bit more consistent and cleaner over the 80 minutes in our own areas.
“We have prepared as normal; it has not been a case of Sean giving us everything he knows about St Helens.
“It is important we do our jobs a little bit better than we have over the past two weeks.”
Seven of Saints dozen Cup wins – two fewer than Rhinos – have come in the summer era although they have not lifted the Cup since 2008.
“I was the losing coach at Wembley that day, so I hope that’s not an omen going into this week,” said Agar, whose Hull FC side fell to a Saints team featuring Long.
“I am surprised it is a while since they’ve won it, given the success they’ve had.”
Granted, given Leeds are missing eight injured first-teamers, including seven of their backline, it will be some feat if they manage to overcome Saints today.
But it gives a glorious opportunity to the likes of Batley-born 19-year-old Jack Broadbent, who has impressed at centre and full-back so far.
He already has fond memories of Challenge Cup ties but from a different viewpoint.
He recalled: “As kids, we used to play on a Sunday and we’d stay up at Batley all day with friends and family playing rugby on the little grass pitch behind the stadium.
“Then we’d all go ball boying and get a fiver each!
“Batley played against Castleford Tigers which was pretty packed out and we always seemed to get Huddersfield too.
“I’m enjoying it (at Leeds). The more I’m getting my hands on the ball, the better I’ll become as a player and Rich (Agar) is giving me the chance to learn, which I’m thriving on.”