Expected goals (xG) is a metric used to determine how likely a player is to score a chance and to calculate how many goals a team is expected to score in a match. The metric was invented in 2012 by Opta's Sam Green and has become commonplace across football analytics. In xG, every shot a player has is given a score between zero and one.
Borussia Dortmund let a two-goal advantage slip late on as they drew 3-3 against St. Pauli in their Bundesliga curtain-raiser on Saturday. Dortmund had Filippo Mane sent off five minutes from time, with goals from Danel Sinani and Eric Smith seeing St. Pauli completing the turnaround at Millerntor-Stadion. Niko Kovac's side took the lead in the 34th minute through Serhou Guirassy's header, though the striker missed a penalty five minutes later to double Dortmund's advantage.