You're 21. You've just scored your first goal for one of the biggest clubs in the world, in the UEFA Champions League, no less. The supporters are bouncing, your team-mates are bounding over. Then you realise: You don't have a clue what to do next. You are Julian Weigl.Dortmund's match away to Sporting CP was 43 minutes old last week when Weigl's moment of brilliance doubled the visitors' advantage. He jinked past Elías before curling a magnificent shot beyond Ruben Semedo and into Rui Patrício's far corner. Not bad for a defensive midfielder. "For the first minute I had my