There weren't many tennis balls that reached the pitch at Old Trafford, but according to the AP news agency, the objects were part of a planned protest against the team's poor start to the season.
Just under 20 minutes into the match, home fans started throwing balls and other small objects as Manchester United were awarded a corner against Roma.
By then, the home side were already 2-0 down. Matias Soulé had plenty of time to put Roma ahead in the 11th minute, and six minutes later Donyell Malen made it 2-0 from the penalty spot.
Booed off
When the referee blew for half-time, the crowd at Old Trafford booed, and few probably believed there would be a turnaround in the second half. That was especially true given that Manchester United had won just two of their 13 games so far in all competitions.
Just over an hour in, United pulled one back, but it took two attempts from the penalty spot to make it 1-2.
Captain Bruno Fernandes' first penalty was weak, but he had to retake it after Roma goalkeeper Devis Vásquez was deemed to have left the goal line too early. Fernandes scored at the second attempt.
In the 83rd minute, United equalised. Matheus Cunha was completely unmarked in front of goal after Roma centre-back Leonardo Balerdi swung at the ball and missed as he tried to clear a cross.
Brazilian Cunha was not finished there. Three minutes later, he also scored the winner to make it 3-2, before being sent off in added time after receiving his second yellow card of the match.
Will Carrick's job be saved?
After nine consecutive games without a win, Manchester United were able to celebrate again, but the question is whether the three Champions League points will save Michael Carrick's job as manager.
On Sunday, Manchester United will face Aston Villa in the Premier League before the international break.
Aston Villa, for whom Swedish national team captain Victor Nilsson Lindelöf played the full match, lost 3-0 to Barcelona in the Champions League on Tuesday evening.
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