Maguire, who looked to have secured a point for United with an 89th minute equaliser, was despondent at the end of a match which piles the pressure on boss Erik ten Hag.
‘Overall on the balance of play we didn’t do enough in the first 60 minutes or so, we started the game not great,’ Maguire said.
‘The first half was pretty even, but when you’re not playing at your best you have to do the basics right and set pieces is part of that.
Harry Maguire looked despondent after Fulham’s late winner at Old Trafford on Saturday
Maguire scored an 89th minute equaliser, but said they were ‘naive’ to press for a winner
‘We knew they would cause us a threat from those areas and they’ve scored early in the second from what we knew – so that’s disappointing on that aspect.’
United started sluggishly in both halves and were made to pay midway through the second when Calvin Bassey hammered in at the second attempt from a corner.
From there United rallied thanks to Maguire’s late goal but it was all in vain and it’s a result that leaves United on the outside looking in in the race for Champions League football.
‘To be a goal behind, I thought our reaction was brilliant especially in the last 30 minutes and when we equalised probably only one team going to win it,’ he said.
‘We were probably naive in the end by throwing too many bodies forward and getting done on the counter attack.
‘We got hit by the injury to Rasmus [Hojlund], who has been big focal point for us but it is up to us to find the solutions and the areas we need to improve on.
Alex Iwobi scored a 97th-minute winner to give Fulham a shock 2-1 win away at Old Trafford
Maguire said the absence of Rasmus Hojlund hurt because the Dane was ‘a big focal point’
‘It’s the story of our season, we’ve been injury hit – as other teams have – and we need to find a solution quick.’
United now turn their attention to the City Ground on Wednesday night as they prepare to face Nottingham Forest in the fifth round of the FA Cup.