Chelsea 1-1 Frankfurt: Hazard seals Europa League final spot after Kepa penalty heroics
The title is confusing. How can one seal the spot in a competition? What does to seal mean here? Is it to cover, or to close, or to mark? Any of its meanings doesn't seem to fit well. I googled for football expressions with seal but found only seal dribble, which is a different story.
Thank you in advance.