UEFA are facing calls for a Champions League round of 16 redraw after an apparent glitch during the ceremony this morning.
Liverpool were paired against RB Salzburg when the draw took place in Nyon earlier today.
First out in today's event was Benfica vs Real Madrid, followed by Villarreal against Manchester City.
But Villarreal were initially paired with Manchester United - which would have been impossible given those sides were in the same group.
There was then a brief delay to proceedings before Atletico Madrid were teed up with a tie against Bayern Munich.
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United were eventually drawn against PSG.
But there remains confusion over whether those conducting the draw on behalf of UEFA put United's ball in the pot as one of the teams to potentially play Atletico.
If that part of the process did not happen, it could lead to issues for the governing body given that it would have altered the permutations and probabilities for the draw.
Manchester Evening News writer Samuel Luckhurst tweeted: "Didn't look like United's ball went back in for the Atletico draw. A sports body would never make a last-minute rule change for a dramatic purpose..."
Independent reporter Mark Critchley posted a clip of the contested moment of the draw, and said: "It definitely looks like #mufc’s ball - in the second pot from the right, back row - was not included in the Atletico Madrid draw."
While journalist James Nalton wrote: "There was a delay confirming the Villarreal v Man City tie after they messed up and put Man United in the pot by mistake.
"Wonder if they were considering re-draw. Then they failed to put Utd in the pot to draw Atletico."
And ESPN's Mark Ogden tweeted: "Issue for UEFA is that the whole thing was played out live on camera. To allow the draw to stand when it was clearly flawed - a genuine mistake, but flawed - would impact the integrity of the competition".
First indications suggested UEFA may seek to press on with the draw in its current form.
Chief football writer of the Independent, Miguel Delaney, said: "From talking to a few within Uefa at moment, early indications are that draw will be allowed stand despite the confusion over United/Atletico, but let's see..."
He then followed up with: "Next question is whether clubs affected - which would directly be United, PSG, Bayern, Atletico, but by extension most of the 16 - want to lodge a complaint."
And Bundesliga expert Raphael Honigstein posted: "Don't see how UEFA can let this draw stand.
"Man Utd were by mistake omitted from the draw against Atletico Madrid."
But a few minutes after the initial wave of reaction ESPN's Alex Shaw reported: "Atletico Madrid are talking to UEFA about the UCL draw. UEFA are currently discussing whether the draw can go ahead in its current guise. Redraw decision coming within the hour is the word."
