Teenager Amad Diallo found the net with his first-ever shot for Manchester United but AC Milan struck in injury-time to secure a 1-1 draw in their Europa League last-16 first leg clash.
The 18-year-old Ivorian, who joined United from Atalanta in January, scored in his second appearance as a substitute with a clever back-header five minutes after his half-time introduction.
AC Milan had two goals disallowed early on but Simon Kjaer’s last-gasp header ensured parity going into the second leg.
United and Milan have been continental champions 10 times between them but must currently make do with Europa League football – though both are on course to return to the elite Champions League next season even if they trail their respective derby rivals Manchester City and Inter Milan domestically.
Whoever progresses is likely to be joined in the quarter-finals by Villarreal, who won 2-0 away to Dynamo Kiev, while Ajax will also be confident after a 3-0 home win over Young Boys of Switzerland.
New Scottish champions Rangers will also welcome Slavia Prague next week with everything open after a 1-1 draw in the Czech Republic.
United returned to action after the high of their weekend derby win over City but were flat until Diallo sparked them into life shortly after the restart.
Bruno Fernandes sent a fine chip over the defence and Diallo reacted superbly to loop a header over Gianluigi Donnarumma for his first professional goal. The youngster was signed for a reported STG37 million pounds ($A66 million) having played less than 90 minutes of senior football.
United’s best chance of the first half fell to Harry Maguire who struck the post from close-range at a corner after Milan dominated the early stages.
Rafael Leao’s opener for the guests was rightly ruled offside and Franck Kessie’s fine strike suffered a similar fate, albeit for handball after video review.
Milan finally had a goal count two minutes into injury-time from Kjaer’s header at a corner which left keeper Dean Henderson looking poor.
Ajax, another former European champion, had second half strikes from Davy Klaassen, Dusan Tadic and Brian Brobbey to thank for their win over Young Boys.
Goals in each half from Pau Torres and Raul Albiol earned Villarreal victory in Kiev, in front of a handful of fans in the Olympic Stadium despite the coronavirus pandemic.
A few fans also saw Nicolae Stanciu’s early stunner for Slavia in Prague but Filip Helander levelled from close-range to keep Steven Gerrard’s Rangers unbeaten in the competition.