Marouane Fellaini scored his first competitive goal for United at Old Trafford, but should he have had another?
The Dutchman would have been able to relax ahead of the final whistle had United put the game out of sight, rather than having to hang on for a 2-1 victory.
Van Gaal told SkySports after the game that three of his players in particular should have converted chances.
"We were not aggressive enough and we did not keep our positions on the pitch. So I was not happy at half-time, and I said at half-time also.
"I think second half was much better. We created more chances. We have to score more goals. We had to finish with Fellaini, Herrera in the first and Wilson in second half.
Between the trio they amassed five shots, half of United's total of 10.
|Total Shots||On Target||Goals|
Van Gaal's comments may seem a little harsh on Fellaini considering he netted his first ever home goal for the club, but the perfectionist he is, he demanded more.
Teenager James Wilson will have been particularly disappointed to spurn his golden opportunity, created through a great run on goal, only to fire wide when the whole of Old Trafford was expecting him to burst the net.
United will have to be more clinical in their next match away at Southampton, with opportunities potentially harder to come by. Prior to their loss to City at the weekend, the Saints had conceded only six Premier League goals all season.