Philly McMahon feels David Clifford was "the one that got away" in his football career.
"I would have loved to mark him," McMahon told Independent.ie's The Throw-In podcast.
"I'm the type of player who asks a manager can I mark certain players. He was definitely on my hit list. How well I would have done against him, I don't know."
Ahead of the 2019 All-Ireland between Dublin and Kerry, there loomed a possible marking role for McMahon on Clifford. Instead, Jonny Cooper got the job, and got sent off in the first half as the two sides drew.
'Clifford, he loves a little bit of separation'
"I'd been studying him all week," said McMahon.
"I studied other [Kerry] players as well. I was looking at little habits, and one stuck out for me.
"I'd been looking at little habits and one habit stuck out for me around his movement. I'll tell you what it was but if I was still playing I wouldn't be telling you!
"Clifford, he loves a little bit of separation. Because he's quite tall, isn't he?
"If you have to mark a tall guy and you have to kind of stand right beside him when he's about to move off, if you can just get some sort of contact it's harder for them to get a second movement.
"So for anybody that's making taller players, that would be the first thing I'd be saying to get after. Can you stop his first run?
"In that first game against Kerry in 2019 what would happen is Kerry would be slow in transition. And he'd come out around the centre forward position and just slowly and slowly go out. Johnny Cooper was marking him at the time and he'd make you think that he's not moving, that he's dormant.
"But as soon as the ball roughly comes across the 45 he's gone, he's moving somewhere. He's either peeling behind, out in front, moving diagonally.
"That's one of the habits that I'd get after. How do I close his space? He's had fellas that have marked him that have been tight, he's had fellas that have marked him that have been fast.
"He maybe hasn't had fellas marking him that have psychologically went after him. And I'm not talking about fellas verbally abusing him, I mean really, really checking him out and testing him.
"I'm not saying that's going to work. You've seen a glimpse of it and him falling into a trap against Tyrone where he got two yellows. I don't think he'll fall for that again but I do think he bites a little bit. And that'll probably change now since I've said that!"
In the first league game of 2020, Dublin - then five-in-a-row champions - faced the Kerry side they had beaten in the previous year's All-Ireland final replay.
"I was supposed to marking Clifford but if [Tommy] Walsh went in because he was a target man, I'd pick him up instead," said McMahon.
"So I picked up Walsh and remember saying to myself, right, do my job, keep Walsh quiet.
"He'd linked the play in the 2019 All-Ireland in the first game. He had his handprint on maybe 1-2 in that first game when he came on. I marked him then when he came on in the replay.
"It was another chance to get my hands on Walsh and see what I could do. So that was my first job. The second job was to see would the fella beside me bite, who was David Clifford.
"I was having a few verbals with him and I'm sure Walsh was looking at me going 'you're marking me, why are you talking to him?'
"But there was still bits where he bit - you know you could say 'fair play to him for standing back up to you' blah, blah, blah but he bit and that for me was something that I always wanted to test.
"I would have definitely, in the last two managements, had conversations before games that I wanted to get a chance to mark him.
"But he's both-footed, he's balanced, his movement in front, in behind, loop balls, he kind of has the whole armoury.
"And the key thing is, for him, has he got the ball going in? Has he got the supply? And has he got the lads around him that will move to give him the space? He has all of that."