Erik ten Hag said Manchester United must be more ruthless after Marcus Rashford struck twice late to send them into the Carabao Cup semi-finals.
United were leading through a first-half Antony strike, but with League One Charlton pushing for an equaliser, Rashford struck in the 90th and 94th minutes to seal the tie.
The win put United into the semi-finals for the third time in four years, but Ten Hag said his players needed to be more clinical, ahead of Saturday's derby against Manchester City.
“In the first half-hour especially, I was quite happy,” said Ten Hag. “I was less happy we were not clinical in front of goal.
“We created a lot of chances. We made a great team goal for Antony, Fred had a good free-kick, but I think we should have scored more in the first-half. We had to fight for it until the end of the game.
"I said before the game - 'no ifs, buts or maybes' - we have to be in that semi-final and we did the job.
"The only thing I wasn't happy with was that we should have finished it earlier by finding that key pass.”
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Rashford took his goal tally for the season to 15 for United and has scored in his last eight games at Old Trafford, which drew praise from Ten Hag.
“When he puts himself in the position where he is one-on-one in the box, he'll score,” said Ten Hag. “That's what he's doing at the moment. When he keeps the focus and keeps putting the same effort in, he will keep on scoring.”
United right-back Diogo Dalot came off injured in the first-half, but Ten Hag said it was too early to say whether he will miss the derby. “Diogo came off, it was a precaution,” said Ten Hag. “We have to see in the coming hours and then make a decision."
