I think if in the next match, one of the teams is infected like the previous players, the game better to stop for a while, and the event staff needs to check all of the teams, including the staff of each team, to make sure that there is no other person who gets infected. That will be too risky if the game continues because some people will say that the match is not fair. But we hope that there is no new case in the football championship in all countries, and the event staff organizer can be careful in handling the event.
Why would wait for another person to get infected before cancelling the games 
? The officials must cancel it right after they confirmed the case. The virus behaves rapidly and it can be passed from person to person and some without even showing early symptoms (because others are asymptomatic). How many people he interact with before finding out that he got the virus? You cannot trace it easily. What more if you let those people interact with new bunch of people. See? May lives are at stake thus they the best move would be an immediate quarantine.