Borussia Dortmund had made enquiries with Juventus about David after Konstantelias was ruled out for months following the cruciate ligament tear suffered on his Bundesliga debut, with Fábio Silva's own future at the club also unresolved amid his growing frustration over game time.
Como had separately shown interest in the Canada international, but it is Atletico Madrid who have moved fastest, with Fabrizio Romano reporting a loan agreement between the Spanish club and Juventus already being finalised.
David joined Juventus on a free transfer from Lille last summer but endured a modest debut season in Turin, managing eight goals and five assists in 46 competitive matches, and had been strongly linked with a Bianconeri exit throughout the closing weeks of the window.
He scored three goals in five appearances at this year's World Cup on home soil, form that had briefly rekindled optimism in Turin before his club form failed to match it.
With David now heading to Madrid rather than the Ruhr, Dortmund face a genuine scramble to find attacking cover before Tuesday's deadline, having already been linked with nine separate candidates to fill the gap left by Konstantelias.
Their search has been complicated further by developments elsewhere: Newcastle's Nick Woltemade, also under consideration, is reported to be heading to Juventus on loan instead, closing off another option just as Dortmund's need for reinforcements becomes more urgent. With time running short, sporting director Lars Ricken's department faces a compressed window to identify a workable alternative before the market shuts.
The chain reaction illustrates how tightly linked the closing days of the window have become across multiple leagues: Atlético's move for David frees Juventus to focus resources on Woltemade rather than competing with Dortmund for the Canadian, while Dortmund - who had signalled only days ago that no immediate decisions would be rushed following Konstantelias's injury - now find themselves needing to move quickly regardless, having effectively been squeezed out of two separate targets within the space of a single afternoon.