The Leeds centre, at 29 now the senior man in Great Britain's squad by age as well as by name, watched his club lose the two major finals of the season knowing that a badly timed ankle injury had ruined his chances of making a contribution.
Senior did the damage a week before the Challenge Cup final, but he and his coach, Tony Smith, made the joint decision to risk it at Cardiff.
"It was a gamble," he says. "Whether it changed the course of the match is an entirely different matter. We made the decision together, but it might not have been the right one. It happened and you learn from these things.
"I'd had an injection the previous day and it had worked superbly. The one I had on match day just didn't work at all. That's something that works sometimes and sometimes doesn't, but it got steadily worse as the game went on."
Senior did not reappear for the second half and watched the Rhinos go down to defeat by Hull from the front row of the stand, inevitably blaming himself to some extent.
The approach for the Grand Final against Bradford almost three months later was different, with Senior publicly ruled out in the week leading up to the big night at Old Trafford.
"I thought at the beginning of the week that, if I wasn't fully fit, it was never going to be an option for me to play on it. I'd taken one chance and it wasn't something I could go through again. Another week could have made all the difference, but making that decision there and then took the pressure off us."
It did not make it a very pleasurable evening for Senior, though. "When the boys walked out of the tunnel, it brought tears to my eyes. I'd kept away from them all week, but it was such an emotional moment for them," he recalls. "There was such excitement in the boys' faces and it was so frustrating not to be involved."
In such a tight match, a centre of Senior's calibre could have made all the difference - an uncomfortable fact that simply deepened his frustration and now has him champing at the bit to get at the New Zealanders on Saturday. "It does make it more important for me. You're only as good as your last game and mine seems a long time ago. I need to put in a big performance in the Tri-Nations."
Even when he was struggling for fitness for Leeds, this competition was firmly in the front of his mind. "If we hadn't had a Tri-Nations coming up I might have pushed a bit harder for the Grand Final," he admits. "There wasn't much point rushing it, because the Tri-Nations was always a more realistic target."
There is little doubt that Great Britain and Brian Noble need him. With the departure of Andy Farrell to rugby union and the long-term injury that has ruled out Paul Sculthorpe, Senior is now Britain's most seasoned Test player.
He made his international debut in the unlikely setting of Fiji almost a decade ago and has been a fixture for the last seven years in a squad that looks very different from his present perspective.
"When I first came into the squad, there were players of 34 and 35 in it. Now I'm the old man at 29; it just shows the wealth of young talent coming through."
Not that Senior is thinking of standing aside in the immediate future or following the example of those who go into international retirement to prolong their club careers.
"I've set myself the target of playing in the World Cup in 2008. If I can do that, I'll be up around 30 caps, which would be a landmark for me."
The immediate task, provided he is fit to win his 22nd cap at Loftus Road on Saturday, is to quell what has looked, on the evidence of their two games against Australia, a fearsome Kiwi challenge.
"Stacey Jones is going to add a lot to them if he plays and this year their outside backs have looked exceptional," says Senior, who also believes that the size of the Kiwis and the intensity with which they play will present opportunities for him and his team-mates.
"They're a big set of boys and you can't expect them to have that intensity for a full 40 minutes of each half. It's up to us to take advantage when the level drops a little bit."
Britain's chances of doing that will improve immeasurably if they have a fully fit Senior on deck at Loftus Road. He will test out that celebrated ankle in a practice match against the England squad today and, if it isn't right, he will, with the benefit of his experiencesthis season, feel honour-bound to say so.
Leeds' season hinged on that troublesome joint; Great Britain's could as well.Reuse content