To have the upper hand is to be in the stronger position. They have the upper hand now.
It describes a contest in progress rather than a finished one, so the advantage can still be lost. The picture is from hand over hand up a stick, where the top grip wins.
1phrasehave the upper handTo be in the stronger position.
“The tenants have the upper hand while the flat stands empty.”
have the upper hand is a phrase.
Practised in Idioms