Forlan and Aguero have formed a formidable partnership
Diego Forlan was given the unenviable task of replacing the irreplaceable when he joined Atletico Madrid in July 2007.
Before signing for Liverpool, Fernando Torres had been Atletico's totem, captaining the side from the age of 18 and finishing five straight seasons as their top scorer.
Yet in tandem with fellow forward Sergio Aguero, Forlan actually managed to take the Spanish side to new levels.
Between them, the South American strikers plundered 35 league goals to fire Atletico into the Champions League for the first time in 11 seasons.
On Wednesday, the Madrid side host Liverpool in what will be their biggest European game to date, with both teams having won their opening two group matches.
Forlan is disappointed there will be no homecoming for Torres, who is absent from Liverpool's squad because of a hamstring injury.
"Everybody here at Atletico still loves him - the crowd, the staff and the players who were here with him," the Uruguayan told BBC Sport.
"He has proven what a great player he is and this is where he started, where he grew up."
Sergio is so good that the biggest teams will always be after him
Atletico striker Diego Forlan
Forlan, who returned from a leg injury to play in Atletico's 2-1 defeat by city rivals Real Madrid last weekend, thinks Aguero can go on to make the same impact as Torres.
Last summer the 20-year-old Argentine attracted interest from Chelsea, Real and Juventus, prompting Atletico to slap a £60m price tag on him.
"Sergio is already among the best strikers in the world and is only 20 years old, so imagine what he can do when he gets more experience," said the Uruguayan international.
"I think he's a great player and will become one of the best. He's very quick, strong, can beat people - he has got everything. He's very similar to Romario in the way he runs and in his style of play.
"He might not be in the race to win the Golden Boot this season but he will be in future.
"It's going to be difficult for the club to hold on to him, just like it was for them with Fernando.
"Sergio is so good that the biggest teams will always be after him."
Aguero has become a fixture up front for Argentina, alongside Barcelona's Lionel Messi, making him a star in his homeland.
His profile was further elevated when news broke in August that he was expecting a child with Diego Maradona's daughter, Gianinna.
Forlan says his strike partner is modest and unassuming. "Sergio just loves football and is enjoying it here at Atletico. He doesn't worry about headlines about his life or about which club he might play for next. He enjoys playing and that's it," he stated.
Forlan and Aguero were on the losing side in last weekend's Madrid derby
The two South America strikers have had to endure Atletico's disappointing start to the season, losing to Sevilla, Barcelona and Real in the league.
But on the European stage there has been no sign of that stuttering form and after their opening two group stage wins against PSV Eindhoven and Marseille, Forlan says Atletico will go all out for victory on Wednesday.
"We are always confident we can win and will go out to win the game," he confirmed.
"Liverpool have very experienced players and have been in the Champions League many times, whereas we are new to this.
"But we have some very talented players, like Aguero, Maniche and Simao, and we know we can win."
The Uruguay international has enjoyed a renaissance since moving to La Liga in 2004 from Manchester United.
He became something of a joke figure during his two and a half seasons at Old Trafford, going 27 games without scoring and notching only 10 goals in England's top flight.
Yet in his first season at Villarreal he won the prestigious Golden Boot, awarded to Europe's leading goalscorer, paving the way for his £14m move to Atletico in 2007.
The 29-year-old was an immediate success in Madrid, scoring 16 league goals and becoming an intelligent, experienced foil for Aguero.
He says there is a simple reason for his success.
"I have always been a confident player, I was confident at United but I didn't have the chance to play," he said.
"When you are on the bench and play 10 minutes, then have to wait a month for your next appearance, it's very difficult.
"The difference is that since I've been here I've been playing regularly and have done really well. It's a different league but there are strong players, just like there are in England."
He believes that is one of the reasons why Torres has enjoyed such success at Liverpool as he set a record for the highest league tally by a foreign player in his Premier League debut season, with 24 goals.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.