Erik ten Hag changed his tone and declared he was happy with Manchester United's overall defending this season, despite criticising his team after their 3-2 loss to Arsenal.
United fell 11 points behind the Gunners in the race for the Premier League title, with Eddie Nketiah scoring a late winner at Emirates Stadium on Sunday.
After that game, Ten Hag said United's defensive failings had been "unacceptable".
Speaking ahead of an EFL Cup semi-final first leg against Nottingham Forest, Ten Hag explained he was talking about defending of the goals specifically and is otherwise pleased with his team's efforts at the back, although there are lessons to be taken on board.
"I think in a lot of games we defended very well, we had a lot of clean sheets," Ten Hag said.
"Against Man City [in United's recent 2-1 win at Old Trafford], we defended very well. I think, in general, also against Arsenal, we defended well.
"I don't think they had many clean shots, I think the one time was from a free-kick. But the rest were shots from distance, when we had a lot of defenders in between the ball and the goal.
"That's what I meant when I said all the goals were avoidable and it can't happen. That was my point: when you concede three goals in a top game, it is very hard to win the game.
"That is what happened so that is one of the conclusions. It can't happen. We set that conclusion... we have to learn and take this lesson."
Ten Hag – who ruled Diogo Dalot, Jadon Sancho and Anthony Martial out of the Forest game – also spoke about the importance of winning trophies, with United hoping to end a run without one since May 2017.
The 52-year-old won three Eredivisie titles, two KNVB Cups and a Johan Cruyff Shield in his time in charge of Ajax, and said: "It's about that, it's about winning trophies.
"We have a good opportunity, but we have to go from game to game. So now we play Forest, two legs, so focus on the first leg and don't think further ahead because that will distract. So the aim for tomorrow is to win that game.
“It is the best feeling you can have, winning a trophy. I had the luck in my career to win some trophies and it was magnificent, especially for the fans. It's so great.
“The fans here, they have some experience, especially the older fans. And now it's a period when Manchester United didn't win any trophies and it's too long ago, so we are aware of that fact. We have to do everything to bring a trophy in."