A disappointing climax at Old Trafford saw AC Milan snatch a stoppage-time equaliser and take a valuable away goal back home for the second leg.
The Reds drew 1-1 with teenager Amad heading home a superbly executed goal in the 50th minute for his first United senior goal but Simon Kjaer powered in a 92nd-minute equaliser just when it looked like we would travel to the San Siro with victory.
Now a place in the quarter-finals is in the balance and captain Maguire remains upbeat but fires a warning to the Reds.
“It is only halfway and we have to stay positive, but we need to play better,” he told BT Sport.