Manchester United boss Ole Gunnar Solskjaer reportedly identified Nathan Ake and Dayot Upamecano as leading targets during the summer transfer window.
The Red Devils have struggled defensively this season but did not bring a new centre-back to Old Trafford before the deadline passed earlier this week.
According to ESPN, Solskjaer wanted his club to sign a new central defender to play alongside Harry Maguire, with Victor Lindelof and Eric Bailly both struggling in the early weeks of the campaign.
The report claims that Ake and Upamecano were viewed by the Norwegian as primary targets, but the former joined Manchester City from Bournemouth while the latter remained with RB Leipzig.
Chris Smalling completed a move to Roma before the deadline, but fellow centre-backs Phil Jones and Marcos Rojo are still at Old Trafford despite not currently being a part of the first-team picture.
The team's defensive options should be boosted after the international break with the return of Axel Tuanzebe from injury, though, while left-back Alex Telles joined from Porto on deadline day.
Matt Law
