Losing 5-0 at home to one of your biggest rivals is a fans' worst nightmare. Weeks of build up, all to be let down in a matter of minutes. Then the aftermath. The bragging rights, the best part of it for victorious fans.
Liverpool were the team inflicting the painful defeat on Manchester United recently and with the wounds still raw, United fans will be extra wary heading into Saturday's derby with City.
Here at Planet Sport, we take a look at some of the most humiliating defeats that dished out to rivals, and we start at Old Trafford.
Manchester United 1-6 Manchester City
An iconic game for many reasons, but also a good starting point considering this match took place ten years and one day before Manchester United were humbled at home by the Reds.
After putting the Citizens ahead, Mario Balotelli revealed his now famous 'Why always me?' vest and the day would only get worse from there for the Old Trafford faithful.
This match was significant as it arguably signalled the start of the power shift in Manchester.
Balotelli, who a day before had set a firework off in his house, opened the scoring as the away team took a 1-0 lead into the interval. Minutes after half-time, Jonny Evans was dismissed and the floodgates opened.
City went 3-0 up before Darren Fletcher reduced the arrears, but then the ten men folded.
Man United boss Sir Alex Ferguson called it "our worst ever day" but it will be up there with the best for the City faithful.
Barcelona 5-0 Real Madrid
Although Jose Mourinho described the defeat not as a humiliation, just disappointing, losing the El Clasico by a five-goal margin was most certainly embarrassing.
Los Blancos sat top of the La Liga standings prior to the meeting and were looking to make a statement, but instead it was Pep Guardiola's men who turned on the style at Camp Nou.
Barca took the lead in fortunate circumstances. Andres Iniesta's coss-cum-shot evaded Marcelo's slide tackle to hit Xavi on the backside and the cultured midfielder waited for the ball to sit up before calmly side-footing it into the net over a despairing Iker Casillas.
Barca's tiki-taka created the second, with Pedro finishing off a fine move.
The beautiful game then took a backseat as two brawls took place.
First, Cristiano Ronaldo and Guardiola were involved as the Barca manager wouldn't let the Portuguese player take a quick throw-in. Then Ricardo Carvalho was fortunate to escape a red card after appearing to elbow Lionel Messi in the face.
David Villa's two goals in three minutes then wrapped up the game for Barcelona.
Substitute Jeffren tapped in a goal in added time to add even more gloss to the scoreline.
It was a match that had everything - apart from a goal for the visitors.
Lazio 1-5 Roma
Roma only lost twice in 2001/02 season but still were unable to defend their Serie A title. However, the highlight of their campaign was undoubtedly a 5-1 victory over fierce city rivals Lazio in the Derby della Capitale.
The two teams, who both play home matches at the Stadio Olimpico, faced their second derby of the season after Roma won their designated home fixture 2-0 earlier in the campaign.
Roma's two most influential players, Francesco Totti and Vincenzo Montella, stole the show for Fabio Capello's men. Totti had a hand in every one of Roma's goals, starting with a trivela cross which was headed home by striker Montella.
Montella would go on to score a first half hat-trick and ultimately embarrass one of Italy's greatest defenders, Alessandro Nesta. He added to the tally in the second half, making him the only player in history to score four goals in the derby match.
Totti added to the tally with the final goal, a stupendous lob.
The 2002 meeting also holds the record for the most aggregate goals (joint with a 4-2 Lazio win in 2009).
Fenerbahce 6-0 Galatasaray
Known as the Intercontinental Derby due to the two clubs being based in the same country but on separate continents, 2002 saw Fenerbahce rack up the biggest win in the match's recent history.
In a day to remember for the hosts, their goals came courtesy of Serhat (2), Tuncay, Ariel Ortega, Ceyhun Eris and Umit Ozat.
Scorer Ortega was sent off but it did not stop the rampant home team as they inflicted the first defeat of the season on Galatasaray.
The win moved Fenerbahce up from eighth to fourth in the standings, but amazingly they still ended the season 26 points behind their rivals.
Chelsea 6-0 Arsenal
It's fair to say Arsene Wenger's 1,000th match in charge of the Gunners did not go to plan at Stamford Bridge.
The 2014 meeting of the west London rivals was notable for the controversial sending off of Arsenal's Kieran Gibbs in a case of mistaken identity. Alex Oxlade-Chamberlain handled on the line to deny Chelsea a goal, but referee Andre Marriner dismissed his team-mate Gibbs.
Brazilian attacking midfielder Oscar then added a double to put the Blues 5-0 to the good in the 66th minute. Five minutes later, Mohamed Salah scored his first league goal for Chelsea after replacing Oscar.
It extended Jose Mourinho's unbeaten run against Wenger to 12 matches, with the Chelsea manager having also inflicted a defeat on the Frenchman in his 500th game.
Celtic 5-0 Rangers
Not the biggest scoreline on show, but this 2018 defeat was such a crushing blow for Rangers as it meant their Old Firm rivals retained their Scottish Championship crown.
Their seventh successive league title cemented Celtic's dominance in Scotland and put them on the brink of winning back-to-back domestic trebles - Celtic would secure their third trophy of the season just a couple of weeks later with a 2-0 win over Motherwell in the Scottish Cup final.
Odsonne Edouard stole the headlines, netting twice. Brendan Rodgers' team showed no mercy and a goal from James Forrest put Celtic 3-0 up at half-time.
Rangers goalkeeper Jak Alnwick made three superb second-half saves but Celtic were not to be stopped and midfielders Tom Rogic and Callum McGregor scored after the break to dish out a chastening defeat to their fierce rivals.
The away team were outplayed in every department and not only did their travelling fans suffer the misery of a five-goal defeat, they also had to witness their fierce rivals celebrate the league title at the final whistle - those who stayed to the end, of course.