As soon as this season's Champions League draw was completed, Group C stood out above all others.
Straight off the bat, there was the prospect of Robert Lewandowski getting an immediate reunion with Bayern Munich after leaving the 2020 champions for Barcelona. The Polish international drew a blank in Bavaria, with Lucas Hernandez and Leroy Sane handing Bayern victory, but will have an opportunity to gain revenge at Camp Nou at the end of October.
That's not the only heavyweight clash in the group, though, and not the only one with a history of players turning out for both sides. After losing home and away to Barca in the 2019-20 group stage, Inter Milan have faced Real Madrid in each of the last two seasons but now have a chance to try their luck against Xavi's team.
As for that 'played for both' element? Well, there are plenty of players who fit the bill.
Perhaps the highest-profile transfer involving the two clubs came back in 2009, when Samuel Eto'o and Zlatan Ibrahimovic switched sides in a player-plus-cash deal. That is far from the only example, though, and Mirror Football has taken a closer look at those who have turned out for both the Blaugrana and the Nerazzurri during their careers.
Some 12 players have turned out for both sides since the launch of the Champions League in 1992, and that's who we will be focusing on here. However, on top of that group you have the likes of Spanish legend Luis Suarez - who played for both in the 1950s and 1960s - as well as the likes of Mauro Icardi who spend time in Barca's academy without making a senior appearance but later made a name for himself at the San Siro.
Who is the best player to turn out for Inter and Barca? Have your say in the comments section
Francesco Coco
For a player with less than 200 league games over the course of his career, Coco doesn't have the worst CV. The left-back started out at AC Milan, spending time on loan at Barcelona before moving to Inter, but quit football aged just 30.
He had been on loan at Barca from Milan ahead of the one World Cup trip of his career, starting against Real Madrid in the second leg of the Champions League semi-finals. The defender would go on to play twice for Italy in Japan and South Korea, including a start as the Azzurri were knocked out by Guus Hiddink's Korean side.
Philippe Coutinho
Coutinho's Barcelona spell was one of those which fans of the club will not want to dwell on. It's hard to pick a low point for a player who left at a loss of more than £100m earlier this year, but his goals against the club while on loan at Bayern Munich might be the answer.
The Brazilian's Inter spell was far more short-lived, and he played fewer than 50 times for the Serie A side. He did make a handful of Champions League appearances, though, including a start in a 4-3 victory over Tottenham Hotspur best remembered for Gareth Bale's hat-trick for the visitors.
Samuel Eto'o
Not only did Eto'o win the Champions League with both Barca and Inter, but he did so in successive seasons. First with the Catalan side in 2009, scoring against Manchester United in the final, and then with Inter in 2010 after Jose Mourinho's team beat Barcelona in the semi-finals.
Eto'o also won the competition with Barca in 2006, also scoring in that year's final, and scored more than 100 goals for the La Liga outfit. His 53 for Inter came over the course of just two seasons, but included a career-high of 37 in the 2010-11 season.
Luis Figo
Like Eto'o, Figo played for Real Madrid as well as Inter and Barcelona. However, the order was more significant, with repercussions still being felt from the Portugal star's move from Camp Nou to the Bernabeu.
Figo's Inter stint came at the end of his career, after winning just one Champions League title with Madrid's Galacticos. He wasn't able to become a European champion while in Italy, but claimed four Serie A titles in his four seasons with the Nerazzurri.
Zlatan Ibrahimovic
It's probably fair to say Eto'o did better out of the 2009 swap deal than Ibrahimovic. The Swede never really saw eye to eye with manager Pep Guardiola in Catalunya, though that doesn't mean the goals dried up altogether.
After helping Inter win three successive league titles, the Swede scored 21 in his first Barca season but was unable to help them overcome his former club in the Champions League semi-finals. He has scored more than 300 goals since leaving La Liga, and is still going strong into his fifth decade.
Maxwell
Brazil left-back Maxwell has been a teammate of Ibrahimovic at several clubs, and the pair traded Inter for Barcelona in the same summer. They'd previously been colleagues at Ajax, and would later spend time together with Paris Saint-Germain.
The South American played just 57 league games in three seasons at Camp Nou, but enjoyed a late-career renaissance after moving on. Indeed, he was at PSG when he made his only tournament squad with Brazil, featuring at the 2014 World Cup.
Martin Montoya
Premier League fans might be most familiar with Martin Montoya for his time at Brighton & Hove Albion. Before that, though, be built a CV including the two European giants.
Right-back Montoya was a graduate of La Masia, coming through the ranks at the same time as the likes of Thiago Alcantara and Sergi Roberto. He joined Inter on loan during the 2015-16 season - his last as a Barcelona player - but the move was not made permanent.
Thiago Motta
Another La Masia graduate, Motta began his senior career with Barca and played more than 100 times for the club. He received a Champions League medal during his time at Camp Nou, though he was an unused substitute against Arsenal for the 2006 final.
The Brazil-born Italian international played a much more active part four years later, though, having joined Inter after spells with Atletico Madrid and Genoa. He started both legs of the semi-final against his former club, though a red card in the second leg meant he wasn't involved as Inter beat Bayern Munich in the final.
Rafinha
Rafinha, like his brother Thiago Alcantara, came through the ranks at Barca and made his name in the first team. His career stalled after an ACL injury in 2015, though, and a loan move to Inter came a few years after that.
His one season at the San Siro saw Inter finish fourth in Serie A, with his only goals coming towards the end of the season against Udinese and Sassuolo. A Brazil international, he joined current club Al Arabi over the summer.
Ronaldo
Ronaldo is another with Inter, Barca and Real Madrid on his CV. However, his spell at Camp Nou was very short if incredibly sweet.
The legendary Brazilian joined Barcelona after a breakout season at PSV Eindhoven and scored an outrageous 47 goals in his only season with the club. Inter pounced and Ronaldo's goals earned them a second-place finish in his debut season, but injuries would plague much of his time in Italy.
Alexis Sanchez
While a number of other players on this list moved directly from inter to Barca or vice versa, it's a different story with Alexis. Some five years passed between the Chilean leaving Camp Nou and arriving at the San Siro, with the majority of that period seeing him turn out for Arsenal.
The former Udinese star won La Liga with Barcelona under Tito Vilanova, but was unable to add a Champions League title. His Inter spell also featured a domestic title, while his efforts at continental glory amounted to an appearance from the bench as Antonio Conte's side were beaten in the 2020 Europa League final.
Arturo Vidal
Like his compatriot Alexis, Vidal joined Inter when his peak years were behind him. The midfielder's final game for Barcelona ended in an 8-2 defeat against Bayern Munich in the Champions League, with a move to Italy awaiting.
Now 35, the Chile international is playing his club football with Flamengo after two years with Inter. His time back in Serie A included a league title in 2020-21 to add to the four he won earlier in his career with Juventus.