Liverpool take on Chelsea in the Premier League this weekend, with Rafa Benitez making his return to Anfield in the away dugout. Eight years ago, he had been in charge of the Reds during a Champions League semi-final clash with Jose Mourinho's Blues. After a goalless draw in the first leg at Stamford Bridge, the tie would be settled by one of the most controversial goals the competition has seen in recent years.
Though not traditional rivals, a simmering tension has emerged between Liverpool and Chelsea in recent years that escalated with a series of high-intensity Champions League meetings. The clubs' first ever European meeting, a semi-final in 2005, lit the touchpaper.
In 2004, the clubs had brought in two of Europe's most highly respected young coaches as they each made their preparations for a bold new era.
The new Liverpool coach, Rafa Benitez, was brought in from Valencia, where he had won league titles in 2002 and 2004. He made a tearful exit from the Mestalla, brought about, he said, because the board's failure to adhere to his transfer requests - "I was hoping for a sofa and they've brought me a lamp," as he famously put it - had undermined his "personal morale".
He had joined the Reds as a champion, but his arrival was rather overshadowed by the exuberant Jose Mourinho, who had lifted the Champions League with Porto in May. At his unveiling as Chelsea manager that summer, Mourinho had earned for himself a nickname that has endured. "Please don't call me arrogant, but I'm European champion and I think I'm a special one," he said. "Not in the bottle with the rest."
For the most part in that first season, Mourinho was the "Special One". His Chelsea side had seized control of the Premier League by November and, in the Champions League, dispatched Barcelona and Bayern Munich as they marched to the semi-finals.
Liverpool, meanwhile, did not even hint at a title charge that season, but they had also booked their place in the Champions League semi-finals - defeating Bayer Leverkusen and Juventus in the knockout stages - as well as reaching the Carling Cup final. There, they were beaten by Mourinho's Chelsea, as they had been in their two meetings in the league.
"They have had a fantastic season," Benitez acknowledged ahead of the semi-final. "They have almost won the Premier League, they unfortunately won the Carling Cup, and they are in the semi-finals of the Champions League. That is enough. You can pinpoint weaknesses here and there, but against Chelsea you need to do everything perfectly if you are to beat them because they have such a good team."
That Chelsea were the favourites was clear. Mourinho described Benitez as "one of the top managers in the world", praising his organisational skills in the quarter-final success over Juventus, but such had been the success of his debut season in England that he was beginning to deem his "Special One" tag unworthy of his abilities.
- John Arne Riise on Rafa Benitez
"At the time I said that, I had just become a European champion, so my ego was up here," he said, moving his hand level with his face. "Now it is even higher."
After the semi-final's first leg at Stamford Bridge, it was the Liverpool manager who took the plaudits as his side nullified the Blues in a goalless draw, but Mourinho's confidence was unchecked. In the days that followed, Chelsea had been crowned champions of England for the first time since 1955, and he remained adamant that they would secure a positive result at Liverpool. "I do not know the feeling of losing semi-finals," he said. "One day I will be beaten, but not this week."
Yet belief was growing at Anfield. Tickets were changing hands for £1,500 each - more than 30 times their face value - as supporters eyed an opportunity to see the Reds return to the European Cup final after a 20-year absence. "I can only imagine what it means for their supporters, so I think the pressure is on them," Mourinho said. "I relish the hostile atmosphere."
Only four minutes into the second leg, amid a wall of noise, the hosts had seized the advantage. Milan Baros beat Petr Cech to Steven Gerrard's flick into the box and lifted the ball over his countryman before being knocked to the ground by the goalkeeper. Luis Garcia nipped it to divert towards goal as William Gallas ran across to clear.
Garcia raced away in celebration, but even with the benefit of countless television replays it remained unclear whether the entirety of the ball had crossed the line. The linesman, though, felt it was a goal, and the Reds were handed the lead.
The visitors would have to chase the game but, despite the wealth of attacking options at their disposal, they struggled to carve out clear-cut opportunities. Benitez, having impressed Mourinho with his tactical acumen in the previous round, had also found the means to stymie Chelsea's chase.
In the first half, Joe Cole managed to lob Jerzy Dudek but missed the target; in the second, Frank Lampard managed to power a low free-kick past the Liverpool wall but not the goalkeeper. However, it was not until deep into injury time that the Reds were truly exposed, when Dudek failed to deal with a header across the box, but Eidur Gudjohnsen drove wide of the goal.
With that miss, Mourinho had been beaten in a European knockout tie for the first time, undone by Benitez's tactical masterclass. "He proved that he maybe is the best manager in the world," Liverpool defender John Arne Riise said. "Tactically, we played a perfect game."
For Mourinho, though, the victory was unjust, and the post-mortem would be dominated by his assertion that his team had been defeated by a ghost goal.
"What can I say to you? The best team lost. That's for sure," he told the media. "They score - if you can say that - they score. We can say the linesman scored. So they were in a position of 1-0 up, and they just defend. They did it well. They were lucky.
"What everybody was speaking about the power of Anfield Road, I felt it. Magnificent. I felt it didn't interfere with players, but maybe interfered with other people. It maybe interfered with the result. You should bring here the linesman and ask him why he gave a goal because, to give a goal, the ball must be 100% in and he must be 100% sure that the ball is in. He made a mistake, and that's life."
For Benitez, it was immaterial whether the ball had crossed the line, given that Cech had appeared to deny Baros a clear goalscoring opportunity in the build-up.
"I have not seen the goal," he said. "I have seen a penalty and red card before, but I have not seen the goal. I don't know if he scored or not, but for me it was a penalty and red card. In the end, it was a good goal."
The nature of the goal mattered little to the Spaniard. After four failed attempts, Liverpool had finally derailed the Chelsea juggernaut, and at the moment when the stakes were highest. Mourinho, having won the UEFA Cup and Champions League during his last two seasons with Porto, would now have to content himself with mere domestic success in his first season in England.
Yet while his team had been unable to unlock the Liverpool defence, he felt no cause to reassess his standing in the game. Asked at his post-match press conference whether he should still be considered the "Special One", he replied: "For sure. You want to try and succeed in your job like I have done in mine inside three years? You have no chance."
What happened next? Liverpool came from three goals down to beat AC Milan on penalties in one of the most dramatic finals ever seen. Mourinho, who was unable to guide Chelsea to a European final before departing the club, has maintained his bitterness over the match-deciding goal. "Overall, I have not been lucky in semi-finals of the Champions League," he said in 2012. "I lost one with Chelsea due to a goal that wasn't a goal. The ball didn't cross the line."