If the two London clubs finish the season level on points, goal difference and goals scored, a play-off will be necessary to decide third place and the automatic Champions League qualification spot.
That scenario could happen if the Gunners win 2-1 at Newcastle and Chelsea draw 0-0 at home to Everton in the final round of matches this weekend, or any scoreline where Chelsea draw and Arsenal score two more goals than them and win by the odd goal.
If this scenario was played out in a European competition, Chelsea would advance because they have beaten Arsenal twice this season.
But unlike UEFA, the Premier League do not take into account the two teams' head-to-head record, much to Cech's bemusement.
"I don't really understand (the Premier League rule)," the Chelsea goalkeeper said.
"I know this is the rule, but we beat them twice over the course of the season - home and away - so a play-off would be really extraordinary.
"The rules are like that. Hopefully it won't happen for both of us."
- Sports & Recreation