This question reeks of an end-of-life product cycle.
Capturing business from the competition is a low-life business endeavor, for such focus means you must have depleted greenfield (or total addressable market), as Greenfield is easier to win than winning from an entrenched competitor is.
Your reliance on stealing market share could also mean you have a commodity product, with minimal differentiation easily stolen away by your competitor.
So, I suggest you create more product differentiation that reestablished and replenishes your addressable market or gets out of the business that is a perceived commodity.
There is no unique and magic voodoo coming from sales or marketing that your competitor cannot acquire (I should know), despite much rhetoric from either. The only meaningful and renewable differentiation of a company is its ever-moving target of a unique product offering.
So, if you are forced to win deals from competitors to make your quota, it means with few exceptions your product is at the end of its lifecycle, needs to be reinvented to address a new greenfield, or kicked to the curb altogether.