From Longman Dictionary of Contemporary Englishhave/gain the upper handhave/gain the upper handADVANTAGEto have more power than someone else, so that you are able to control a situation Police have gained the upper hand over the drug dealers in the area. → upper
Examples from the Corpus
have/gain the upper hand• But slowly and surely the followers of Chaos gained the upper hand.• If the two had been introduced simultaneously, the larger one would invariably have the upper hand.• Now White gains the upper hand.• The world can only pray that they do not gain the upper hand.• Under the proposed law, she would have the upper hand.• We must destroy them now, while we yet have the upper hand.• When you have a gun you have the upper hand, it makes you feel big, bad.• Police have gained the upper hand over the drug dealers in the area.• Officials said they might reopen the freeway at 5 p. m. today, perhaps sooner if firefighters gain the upper hand overnight. 