With David and Philipp Degen potentially becoming the first twins to meet in a UEFA competition game, UEFA.com looks back at matches that pitted brother against brother.
If David and Philipp Degen feature in Wednesday's UEFA Europa League Group H game between BSC Young Boys and VfB Stuttgart, they will be the first twin brothers to come face to face in UEFA competition.
Right-back Philipp is on a season-long loan with Stuttgart from Liverpool FC, while David is back in Switzerland with Young Boys following a brief spell in the Bundesliga with VfL Borussia Mönchengladbach. "We have played against each other twice in the past, but not for very long," said forward David. "
It will obviously be a special match for us. It doesn't happen every day that twins meet in European competition." In fact, it would be a first.
Philipp added: "Obviously it is very special because I will be playing against my brother. However, I cannot think about him and his side's chances because we have come here to take all three points. We have played each other twice before. I started on both occasions whereas he came on as a substitute. I won both games.
We have a very experienced team so I don't think anybody needs advice on how to defend against my brother."
Should the twins take the field at the Stade de Suisse, they will become only the fourth set of siblings to appear on opposite sides in UEFA club competition fixtures. UEFA.com looks back at European football's previous Cains and Abels.
Erwin Koeman and the younger Ronald figured in the Netherlands' 1988 UEFA European Football Championship-winning squad, but found themselves in opposition during the 1988 UEFA Super Cup as Erwin's KV Mechelen – winners of the 1987/88 UEFA Cup Winners' Cup – surprisingly overcame Ronald's PSV, then European champions.
On the pitch no brotherly love was lost. "If necessary, I will bring down Erwin," Ronald once said. "Maybe I go in even harder because he is my brother. I don't want him to beat me." Not that beating his sibling was ever much of a pleasure. "When I beat him in a board game or something he used to drive me mad because he acted like he didn't care," Ronald remembered. "I couldn't stand that."
The Riises came into direct confrontation in the 2009/10 UEFA Europa League group stage, with left-sided John Arne running straight at right-sided midfielder Bjørn Helge in Group E. John Arne's Roma prevailed in each of the fixtures, yet little brother Bjørn Helge's team ended up reaching the final, losing to Club Atlético de Madrid.
The older sibling by three years, John Arne relished the prospect of taking on Bjørn Helge before that first meeting, saying: "I always look forward to playing against someone I know and I know my brother better than anyone. My brother and I are room-mates when with the Norway team. Like every young player, he has a lot of tasks such as carrying the balls and dealing with the kit. In our room we have a lot of competitions which I can't go into detail about, but for us it's competition time again."
Gabriel and Diego Milito
FC Barcelona 1-0 FC Internazionale Milano
28/04/10 UEFA Champions League semi-final second leg
Barcelona centre-back Gabriel never got off the bench in the first leg of last season's UEFA Champions League semi-final, watching his side lose 3-1 to the soon-to-be European champions, and while he was able to face striker brother Diego in the return match, his victory was a hollow one.
The brothers had been in competition before back in their native Argentina, where Gabriel's CA Independiente used to encounter Diego's Racing Club, and the former recalled how passions boiled over in one infamous Buenos Aires derby. "The referee had to pull us apart because we kept on shouting terrible things at each other," he said. "It was fairly childish behaviour, like we were kids at home."