Liverpool may have claimed a major advantage in their UEFA Europa League round-of-16 clash after beating Manchester United 2-0 on Thursday, but manager Jurgen Klopp is afraid referee Carlos Velasco Carballo may yet spoil their party.
The Reds have one foot in the competition's quarter-finals after triumphing in Thursday's first leg, but Klopp is fearful Carballo, whom he sees as too card-happy, could ruin their tournament run, per the Mirror's Alex Richards:
We don't have to criticise the referee because tonight he didn't decide the game. But for the whole tournament, it's difficult if you get a referee [like this].
I think there were a few yellow cards on both sides where you thought 'why'? Now we have all the bookings and the team who will go through will have the problem in the next round with the yellow cards so that was really difficult tonight.
Liverpool pulled through Thursday's first-leg assessment at Anfield with flying colours, and that 2-0 win went a long way to avenging the pair of Premier League defeats Klopp's side suffered to United already this season.
However, the German is already thinking toward the next stages of the competition and how his squad selection may be affected if Carballo becomes tempted to caution players:
We didn't know how to handle it because we didn't know for what? And then you saw Dejan [Lovren] was close to a second yellow because he was not satisfied with his yellow card.
It was really hard for a centre half in an atmosphere like this with a yellow card, for Hendo with such an early yellow card.
As I say it didn't decide the game tonight but each team who will go through will take these yellow cards with them and that's not too good.
The Spanish official handed out a total of six yellow cards on Thursday split evenly between the two teams, with Jordan Henderson, Dejan Lovren and Philippe Coutinho the culprits for Liverpool.
Defenders Lovren and Alberto Moreno sit on two yellow cards apiece and would incur a one-match suspension if either were to pick up a third in the second leg against United next Thursday at Old Trafford.
With so much at stake and the volatile nature that often comes part and parcel when Liverpool meet Manchester United in any setting, one might suspect Carballo will be reaching for his pocket.
Prior to the first-leg meeting, Unibet provided a breakdown of Carballo's recent record in disciplinary matters, which could be interpreted to support Klopp's suggestion:
Nevertheless, Liverpool did benefit in a big way from one of the referee's biggest calls in the first leg, when Memphis Depay fouled Nathaniel Clyne right on the edge of the Manchester United area.
Carballo awarded the penalty, which Daniel Sturridge stepped up to convert, and former Premier League referee Graham Poll wrote in his Daily Mail column that it was the correct decision:
Referee Carlos Velasco Carballo was absolutely correct to award Liverpool a penalty.
While the initial contact on Nathaniel Clyne from Memphis Depay was outside the area, the following contact was either on the line - and the line constitutes part of the area - or just inside the box depending on the viewing angle.
Klopp will hope those 50-50 decisions continue to run in favour of his side and that they also manage to keep cool heads in the second leg while sacrificing none of their intensity in the process.
The Reds chief is wise to have one eye on ensuring he has sufficient resources to keep advancing in the contest, of course, but Liverpool's first task will be to dust off the threat of Manchester United on Thursday.