After weeks of negotiations, the competitor managed to trump our hand with a last-minute deal.
После недель переговоров конкурент смог победить нас сделкой в последний момент.
Definitions
To trump (someone's) hand means to surpass or outdo someone's effort, plan, or advantage, often by presenting something better or more effective. The phrase originates from card games, where 'trumping' means playing a higher card to beat another player's card.