Back in the contest
I hear the commentator say "in the contest" when they score. What does it mean?
Arsenal are back in the contest.
The contest refers to the match between the two sides. So, to be back in the contest means that a team now has a chance in the game. Imagine a team is losing by two goals but then score to make it 1-2 - they are now back in the contest (the match) they now have a chance of getting something from the match (a point or maybe three).