Ole Gunnar Solskjaer believes goalkeeper Dean Henderson should have saved AC Milan's late equaliser at Old Trafford.
The Manchester United shot stopper was beaten in stoppage time as Simon Kjaer headed a deserved equaliser for the Italians.
It cancelled out Amad's second-half opener, but questions will be asked of Henderson who was beaten relatively centrally.
Solskjaer has also pinpointed the defending that allowed the Milan defender to get an effort on goal, but did question his goalkeeper.
He told BT Sport: "Its a header from six yards. He can save it of course, I've seen him save them.
"But it is the structure that we lose. We drop deep and we get blocked off and Kjaer makes a good run.
"We should've attacked the ball with the men we had."
Henderson is currently enjoying a run of games with David de Gea absent as he looks to stake his case to usurp the Spaniard as United's first choice.
Milan's late goal means they hold the advantage ahead of the return leg at the San Siro next week.
The Serie A outfit enjoyed large spells of dominance and it was only VAR who denied them an opener.
Franck Kessie was deemed to have controlled the ball with his arm and his strike was ruled out.
United were unable to carry their excellent form from the Manchester derby win into Thursday's Europa League encounter.
Solskjaer admitted they were "a long way off" as he urged them to continue learning.
He added: "We were a long way off. Possession was 50:50 but we were too slow with the possession.
"It is sometimes hard off the back of a game we had (on Sunday) but that is the learning we have to get into ourselves and perform every week."
