Back in 1998, on the eve of the Challenge Cup final, the strong-running centre was gearing up ahead of what still remains the biggest-ever shock in the competition’s 123-year history.
Eagles, of course, in only their third season in the top-flight and given no hope by anyone apart from themselves, stunned star-studded Wigan with a 17-8 win that continues to mystify.
Senior, just 22 at the time and before establishing himself as one of the sport’s finest three-quarters, returns today as Sheffield assistant coach.
Granted, it is not for the Challenge Cup final; the South Yorkshire club never did take off quite as much as hoped after the famous maiden Wembley win.
But the inaugural 1895 Cup final against Championship rivals Widnes Vikings, which takes place after the main event of Warrington Wolves v St Helens, is something to cherish nonetheless.
Senior, though, has had an unusual build-up to the event.
Since Monday, he has spent five days on a bike, fundraising for Rugby League Cares, along with 24 other riders as they embarked on the gruelling UK Red Ride to Wembley.
An arduous challenge of 340 off-road miles from the George Hotel in Huddersfield - the birthplace of both rugby league and Senior - they navigated some of the country’s toughest terrain before arriving at the Rugby League Legends statue at Wembley yesterday afternoon.
With a well-deserved Budweiser in hand, the 43-year-old former Leeds Rhinos and Great Britian star had little time to savour the moment.
Instead, he was joining up with his Sheffield players and staff as they embarked on a stadium tour and made their own final plans.
Speaking to The Yorkshire Post earlier during his odyssey - a particularly difficult day’s riding on Wednesday - Senior said: “I absolutely bloody hate it (cycling)!
“I’ve not been on a bike since the first time we did this.
“This is the third time. I did it the first year, my missus did it last year and now it’s my turn again.
“It’s been quite a traumatic day today - we’ve done just over 80 miles and the support crew with (Head of Rugby League Cares) Chris Rostron has been absolutely terrible.
“We missed our dinner because they weren’t there in time. They know when I don’t get fed and I’m tired I get very, very grumpy so it’s been a tough day for a lot of people!
“People are out of their comfort zone and there’s different abilities and characters but it’s all done for a great cause.”
The charity, whose mission is to “enhance and enrich people’s lives through the power and positive influence of Rugby League”, completes all sorts of work.
For instance, it has been offering support this week following the tragic death of Archie Bruce, the 20-year-old Dewsbury Moor player who died just hours after making his debut for Batley Bulldogs in Toulouse last Saturday.
Senior explained: “The RFL Benevolent Fund is helping out the family but Rugby League Cares is stepping in as well for the friends, family and also the players who were out there.
“At the end of the day it’s a traumatic thing to read on a Sunday morning on social media.
“But to be his team-mate - to play with him, be involved on his debut, see what happened - it can be quite a traumatic thing, too, and you don’t know how it can affect some people.
“Rugby League Cares will be on hand to make sure if anybody needs anybody to speak to the assistance will be there.”
Part-timers Sheffield, meanwhile, are coached by the legendary Mark Aston, Mr Sheffield who won the Lance Todd Trophy as man-of-the-match against Wigan and has spent most of the intervening 21 years helping drive the Eagles in one way or another. Senior joined Leeds the year after Wembley and scored 171 tries in 365 games for the Blue and Amber, lifting four Super League titles and becoming a Great Britain regular.
He linked back up with Aston at Sheffield in 2013 but said: “I’m not involved in any of the coaching sessions this week.
“Tubbs (Aston) and the other coaches are doing that. I’m away from it all.
“But nothing is going to change at the end of the day.
“What we do this week in training sessions is irrelevant; it won’t change anything and the boys will be fired up and ready for it.
“The sessions this week will be the easiest we’ve had all year.
“I’ll be literally jumping off the bike (on Friday), jumping on with Sheffield and going to do the stadium tour with them.
“I’ll go to the team hotel later on the evening for the shirt presentations and the meetings.
“On Saturday, the rest of the cyclists will be doing corporate - so I’ll be missing the best bit!
“But we’re aiming to get there just after the final kicks off - about quarter-past three - so we’ll let everything die down, let the boys watch some of the game and savour that atmosphere before they go get ready.”
The 1895 Cup, which has been formed for Championship and League 1 clubs, has come in for criticism due to scheduling issues and costs.
But Senior maintained: “This is a great opportunity for part-time players to get the thrill and adrenaline of playing on the hallowed turf.
“They don’t come around very often.
“It’s a concept that’s in its infancy and we’ll see how it goes.
“With it being after the Challenge Cup final, the good thing is the players will actually be warming up literally as the winners get the trophy and do their lap of honour so they will be able to experience the game as it’s been played and the atmosphere.
“It’s worth it just for that and I’m pleased for the boys for the hard work they have done this year; they deserve their day in the sun.”
And what about Senior’s day in the sun back in 1998?
“I just remember coming up against the mighty Wigan, the biggest odds-on favourite ever to lose the final, and how everyone had written us off,” he said,
“And I remember the team meeting we had before with (coach) John Kear.
“He’s coming Friday night to do our shirt presentation which will be really nice for him and the boys as well.
“No doubt he’ll be having his words of wisdom – which he is very, very good at – to get the boys excited and fired up.
“But for me the atmosphere - walking out of the tunnel and the warm-up - is probably the best memory of that and all big games for me.
“You can take in the atmosphere and really appreciate everything around you.”
To support Keith Senior and Rugby League Cares. follow this link https://www.justgiving.com/fundraising/Keith4Senior