Pecker is a key witness in the case against the former US president, who is accused of falsifying business records to cover up hush-money payment
Three other fixtures were also played behind closed doors, including Wolverhampton Wanderers' 1-1 draw at 10-man Olympiakos.
The match in Athens was given the go-ahead despite the Greek club's owner Evangelos Marinakis saying earlier on Thursday he had contracted the virus.
Bayer Leverkusen celebrated a 3-1 win at Rangers in front of a full house at Ibrox and Istanbul Basaksehir fans rejoiced after an 88th-minute penalty by Edin Visca gave them a 1-0 home win over FC Copenhagen.
Striker Odion Ighalo fired Manchester United ahead in the 28th minute as he juggled a Bruno Fernandes pass onto his left foot and unleashed a thunderbolt into the top corner from 18 metres.
Daniel James doubled the lead when he side-stepped his marker and buried a crisp low shot into the bottom corner, leaving keeper Alexander Schlager rooted to the spot.
Juan Mata made it 3-0 with a clinical finish from 10 metres after 82 minutes before substitutes Mason Greenwood and Andreas Pereira put the icing on the cake in stoppage time.
United manager Ole Gunnar Solskjaer praised his team for stretching their unbeaten run to 11 games in all competitions in unfamiliar circumstances.
"It was a weird atmosphere and the boys were so focused and created their own atmosphere and I think the camaraderie and the team spirit was there to see," Solskjaer told BT Sport.
"It's not to recommend (football behind closed doors) but I have to praise the boys because they did fantastic."
Olympiakos, who knocked out Arsenal in the previous round, had centre back Ruben Semedo sent off in the 28th minute for a last-man foul but Youssef El Arabi fired them ahead in the 54th with a close-range finish.
Pedro Neto levelled with a deflected shot from 23 metres as Wolves piled on the pressure after the break.
Rangers fell behind to a 37th-minute Kai Havertz penalty, given after a lengthy VAR check as George Edmundson handled a Charles Aranguiz cross.
Aranguiz scored midway through the second half as he drilled in a half-cleared cross before Edmundson pulled one back for Rangers, heading home a James Tavernier corner.
Substitute Leon Bailey put Leverkusen in the driving seat to reach the last eight with a classy late goal, leaving his marker flat-footed with a cheeky dribble before curling a sublime shot past goalkeeper Allan McGregor.
Swiss side FC Basel stunned Eintracht Frankfurt 3-0 away behind closed doors, as Samuele Campo curled in a 27th minute free kick before substitute Kevin Bua made it 2-0 and set up Fabian Frei to drill home the third.
Shakhtar Donetsk took full advantage of an empty ground at Vfl Wolfsburg and beat the German side 2-1 thanks to goals from Junior Moraes and Marcos Bahia, who cancelled out John Anthony's Brooks effort for the hosts.
Viktor Kovalenko missed a penalty for Shakhtar before Wout Weghorst also squandered a spot-kick for Wolfsburg in an eventful first half.
Two matches were postponed as Spanish side Getafe refused to travel to Italy and face Inter Milan while AS Roma said they could not travel to Spain to play Sevilla because of flight restrictions.Results
LASK 0 Man United 5
Frankfurt 0 Basel 3
Basaksehir 1 Copenhagen 0
Wolfsburg 1 Shakhtar 2
Rangers 1 Leverkusen
Olympiakos 1 Wolverhampton 1
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