BLOOD is thicker than water, but not so for Rhyce Shaw and Sam Reid, who will be placing team over family tomorrow night.
While Sydney battle to overcome their top-four hoodoo, the Swans pair will be waging a personal war against their brothers Heath Shaw and Ben Reid.
There are 19 sets of siblings playing at different clubs this year so the concept of brother against brother is not unfamiliar. Round two saw Jarrad McVeigh play against his brother Mark from Essendon.
But having two sets of brothers playing against each is so rare that the AFL yesterday could not recall whether it had happened before.
John Longmire has said it's unlikely Rhyce will be asked to tag Heath but the Reids are bound to lock horns as Sam is a forward and Ben is a defender.
''It will be a bit strange,'' Sydney's Reid said yesterday. ''I got a small taste of it at pre-season - it's a pretty weird feeling.''
Fans have already had a glimpse of Rhyce and Heath's sibling rivalry in 2009 when Paul Roos, with the match already lost, threw his recruit forward in the dying minutes of a game.
''I led out on centre wing and Heath spoilt the ball out of bounds and I fell over,'' Rhyce said.
''It was only for five minutes. Roosy saw the funny side of it and matched us up against each other.''
Rhyce would love the opportunity to shut down his brother, who is one of the best rebounding defenders in the game, though Longmire is likely to use his pace in a more creative role.
''Knowing Heath so well, I probably know the intricacies of his mindset and where he likes to run,'' Rhyce said. ''It'd be a good challenge because he's one of the best players running around, if not the best half-back. It'd be good fun too because I'd give him … a few hits in the guts.''
Rhyce said neither he nor Heath would take a backward step if they went toe-to-toe tomorrow.
''If it came to blows, we'd have a go, I reckon,'' Rhyce said.
And it's not just on the football field where Rhyce, who is nearly four years older than Heath, has terrorised his brother. A nets session once ended with Heath in tears vowing never to play cricket with him again.
''I was a pretty fast bowler when I was younger,'' Rhyce said. ''He had the pads on, I had a brand new two-piece pill and steamed in and hit him with a bouncer flush right on the chest and he walked all the way home crying with his pads and bat.''
As hard as it would be to imagine now, the 195-centimetre Sam Reid was a late developer and, as the self-confessed ''runt'' of the team, played as a ruck-rover in his early junior career. He was also a ''punching bag'' for his brother at home.
''I had my growth spurt when he was at Collingwood, so I never really had a chance to match him physically or beat him up,'' Sam said.
''He was always on top of me in sport and around the house.
''I remember being younger he used to get really angry when he got beaten on the Sony against the computer and he'd pretty much take it out on me.''
Tomorrow, Sam will get his chance to exact some revenge on Ben.
''Once you cross that line, you're a Swan, you're a Blood,'' Sam said. ''You want to back up your teammate before you back your brother up.''