Toto Wolff confirmed that Mercedes held talks with McLaren earlier this year about a possible engine supply deal, but ultimately logistics scuppered the opportunity.
For McLaren, the writing was on the wall as soon as pre-season testing in Barcelona, when Honda's new power unit proved to be just as uncompetitive and unreliable as its previous engine.
From the outset, the Woking-based outfit sought an alternative solution for 2018, with long-time McLaren shareholder Mansour Ojjeh approaching at one point close friend and Daimler chairman Dieter Zetsche to inquire about a potential partnership with the German manufacturer.
But supplying a fourth team, especially on such short notice, was always going to be a tall order for Mercedes.
"We wanted to give McLaren an engine, the problem is that it dragged on for a long time and we just didn't have the structure in place and the capacity to supply them an engine for 2018," Wolff told ESPN.
"It was simply too late."
Wolff would not rule out however renewing Merrcedes' association with McLaren in the future, the pair having enjoyed a prosperous relationship for the better part of twenty years, between 1995 and 2014.
"You must never rule out supplying anybody in the future and this is why McLaren or anyone else in the future could be a partner."