Thirteen matches is a long time in football.
To give it some context, if Arsenal were to fail to win any of their next 13 then it would take them through to the middle of January.
It is a run of games long enough to return fair judgement.
So what are we to make of the 13 competitive games in which Arsene Wenger has failed to beat Jose Mourinho?
Mourinho, you can assume, knows how to get the better of a Wenger side, or - after seven victories and six draws - at the very least not allow them to get the better of his.