United drew 1-1 with defending champions Bayern Munich at Old Trafford this evening.
The manager told ITV Sport: "The players played really well so we're delighted but just a bit disappointed that we conceded in the end.
"There was a real determination to make sure we did well, the players realised we were playing a really good side tonight.
"We know we've got to score a goal in the second leg. We have to do something about it. But we know we've given ourselves a great opportunity."
The Premier League champions will have to score at the Allianz Arena in next week's second leg if they are to make the last four.