Ole Gunnar Solskjaer made it five wins out of five on Saturday as Manchester United beat Reading 2-0 in the FA Cup third round.
Juan Mata and Romelu Lukaku grabbed the goals for the Red Devils, whose starting line-up featured nine changes from the Newcastle victory in midweek.
Defensively Solskjaer was short of options, so Matteo Darmian - a right-back by trade - was forced to play out of position alongside Phil Jones at centre-back.
It saw Reading dominate possession and have five more shots than United (13), which Solskjaer wasn't very happy about.
"It was always going be hard with my team selection," said the former striker, per the Irish Times. "I made it hard for the players to be fair on them, because it's a team that's never played together.
"Some players like [Darmian] played out of position but I thought he was excellent. Reading made it really tough for us. We never had a kick the first five minutes.
"They just kept possession and we weren't cohesive enough in the pressing. That happens when you don't have a team that doesn't play together as much.
"We didn't have too much time to work. The pleasing thing is we're through and it's another clean sheet. Two-nil flatters us because I think they played some great stuff."
United looked shaky at the back against Reading and it's become clear that Solskjaer - who is only interim manager at the moment - wants to make reinforcements in January.
According to The Sun, Solskjaer will speak to chief executive Ed Woodward about signing £45m-rated centre-back Nikola Milenkovic from Fiorentina this month.
Milenkovic, 21, has hugely impressed in his two seasons in Serie A and Solskjaer has identified him as someone who can improve United's defence.
It all depends on whether Woodward is prepared to fork out £45m midway through the season, which is always a tough time, though it's claimed he's open to making the right signings.
This will be music to the ears of United fans, who firmly believe the likes of Jones, Chris Smalling and Marcos Rojo simply aren't good enough anymore.
Eric Bailly is arguably the only top-class centre-back in United's ranks, so bringing in someone like Milenkovic would be a step in the right direction.