In late June, Instacart CEO and founder Apoorva Mehta had a message for DoorDash: After weeks of discussions between the two companies about a possible merger, Mehta told his counterparts at the meal-delivery company that the talks were off, according to several people with knowledge of the matter.

But the talks weren’t off. In early July, Instacart reached out to DoorDash again to say that the company wanted to revive their merger discussions. Around the same time, Instacart representatives informed DoorDash that Mehta, who had struggled with turnover in the company’s product team, would soon be stepping down as Instacart’s CEO. Within days, there was a new face representing Instacart in those discussions: Fidji Simo, an Instacart board member whom the company announced on July 8 would replace Mehta as CEO of the high-profile grocery-delivery startup, according to three people familiar with the matter.