The Video Assistant Referee [VAR] was once again in the firing line after another controversial night in the Champions League.
UEFA brought forward the use of the technology for the last-16 stage of this season's competition , and the controversial system has caused more consternation.
In the first round of fixtures, Ajax were furious after their opening goal against Real Madrid were ruled out for a controversial offside call .
But on Wednesday two sides were a victim of the technology.
Carlos Del Cerro Grande, the referee for Manchester City's first leg trip to Schalke, was at the centre of the confusion after a penalty was awarded to the home team in the first half.
Leading via Sergio Aguero's goal, the hosts had the chance to draw level when Nicolas Otamendi handled Daniel Caligiuri's goal-bound shot.
A corner had seemingly been awarded but VAR intervened to give a penalty, delaying the game being restarted by nearly three minutes before Nabil Bentaleb was permitted to step up to make it 1-1.
Commentating on BT Sport , former Arsenal defender Martin Keown lamented: "It is the length of time this is taking.
"The spontaneity of football is in danger of being lost here. We want quicker decisions, please."
Rio Ferdinand, formally of England and Manchester United, added: "This is the problem with VAR. It takes so long to make a decision."
And he was not the only one to be confused by the time taken to make the call:
Central to the delay was a problem with the pitch-side screens which officials can refer to help make decisions.
Those monitors were out of action which prevented Cerro Grande from giving an immediate decision, forcing the significant delay in Gelsenkirchen.
By the end of a remarkable opening 45 minutes, Schalke had turned the game around when Bentaleb struck home a second penalty after Fernandinho was adjudged to have tripped Salif Sane - this time given without the assistance of VAR.
Though City were aggrieved and later lost Otamendi to a red card in the second half, they turned the game around late on via a stunning free-kick from Leroy Sane and a smash-and-grab winner from Raheem Sterling in the 90th minute to win 3-2.
In Spain, there was further indecision as VAR got involved again.
Alvaro Morata looked to have opened his account in his second spell at Atletico Madrid with a bullet header against Juventus in their first leg at the Wanda Stadium.
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Felipe Luis crossed from the left and the on-loan Chelsea forward rose above Giorgio Chiellini to thump into the top corner.
But after the celebrations had concluded, official Felix Zwayer was urged to consult one of the pitch-side screens - in full working order in the Spanish capital - before resuming play.
Morata appeared to put two hands on Chiellini as he headed home, leading to the Italian throwing himself to the floor.
And German ref Zwayer was swayed by the centre-back's reaction and awarded Juve a free-kick.
It was the second time Morata had seen a goal against a former employer ruled out after his effort against Real Madrid in La Liga was also chalked off.
Naturally, the incident did not escape the watchful gaze of many on Twitter.
VAR had already come to Juve's aid when Mattia de Sciglio's foul on Diego Costa in the first half was adjudged not to have taken place inside the penalty area, after Zwayer had given a spot-kick to the home side.
Much like City, Atletico emerged from the ashes of the VAR mess to prevail to make themselves favourites to progress to the quarter-finals.
After Jose Gimenez had given Diego Simeone's side the lead, centre-back partner Diego Godin doubled the lead via a deflection off Cristiano Ronaldo, to give the La Liga side daylight ahead of the second leg.