Basically, I've been watching #BraGer in the BBC commentary, because I wanted to know what impartial commentators had to say (except for, I was surprised to hear, rather offensively misidentifying the German anthem). In the second half, when it's 5-0, the commentator says: "I think Germany might declare at any moment." Now, I'm familiar with a number of meanings of "declare" and expressions involving it, but I'm not fully sure what this is about except that I don't think it's something from football.
I found references to "declaring" having something to do with cricket matches being finished early - could it be that, or is it something else? My knowledge of cricket is non-existent except that people have to wear exactly the right kind of clothes (thank you, Dorothy L. Sayers), there are wickets, and people run around the field like in what is called "Brennball" in our schools.