Six reasons why the Copa Libertadores final between Boca Juniors and Fluminense is a must-watch

Sergio Romero knew little other than frustration at Manchester United. The goalkeeper spent the majority of his six years at Old Trafford sitting on the bench, featuring just six times in total in the Premier League.

However, Romero is certainly enjoying his football again, having quickly attained hero status since joining Boca last year - primarily because of his penalty-saving prowess, which is the main reason why the Argentines are in the Libertadores final.

Indeed, Boca haven't won a single knockout game, drawing all six of their outings in the last 16, quarters and semis. However, they've now won three shootouts in a row thanks to Romero, who has saved six spot-kicks so far, while at the same time keeping five clean sheets - no other goalkeeper has more.

As a result, the former Argentina international now rather understandably believes that Boca are destined to triumph at the Maracana. "I have faith that things are going to work out for us," Romero says, "that we're going to win it."

If Boca manage to make it to penalties yet again, you certainly wouldn't back against them - or their shootout specialist.

There's no denying that Edinson Cavani will be the most high-profile attacker on the field at the Maracana. The Uruguayan is undoubtedly one of the finest forwards of his generation, having scored goals at club level in Italy, France, England and Spain, and won a Copa America with his country.

Cavani hasn't quite caught fire since joining Boca at the end of July, but his pedigree cannot be questioned, and it's worth pointing out that one of his three goals to date did come in the second leg of the semi-final against Palmeiras.

Nonetheless, it is Fluminense's veteran striker who is being touted as the likely match-winner on Saturday - even though many football fans outside of South America are unlikely to have ever heard of him.

German Cano is the quintessential journeyman, having spent the majority of his career moving from one club to another, often on loan. He never represented Argentina at any age group and, truth be told, many thought he was finished after suffering a serious knee injury at Pachuca in 2015.

However, Cano says now that "It helped me gain experience, become a better player, work much harder. You learn from those experiences. I’ve enjoyed everything I've been through. I’m older now and, today, I’m in very good form." That's putting it mildly.

Cano is the Libertadores' top-scorer, having scored as many goals (12) as the entire Boca team - and in fewer games (11). One could also argue that, right now, there is no better first-time finisher in world football, given 25 of his 36 goals in all competitions this season have come without the need for a second touch.

Cano, then, is buzzing with self-belief going into what is, by some distance, the biggest game of his life. "We know that victory would go down in Fluminense’s history," he said. "It would be really beautiful because it has taken us a long time to get there." It's taken him longer than most, though, and many neutrals are hoping that his inspirational perseverance pays off on Saturday.

Despite long dreaming of a move to Europe, midfielder Andre promised Fernando Diniz in January that he would stay at Fluminense until the end of the 2023 season. Nonetheless, he was sorely tempted to leave when an almost "irrefutable proposal" arrived during the summer from a "club that plays in a big league".

Andre ultimately stayed put, partly because Fluminense were still in the Copa Libertadores, and partly because it was the "right thing" to do in the circumstances. However, the midfield playmaker also trusted Diniz when the coach told him that if he stayed, his value would increase - and it most certainly has, along with the interest in the 22-year-old's services.

Indeed, according to the latest reports, Arsenal have now overtaken Liverpool - the club believed to have submitted that big summer bid - in the race to sign Andre during the January transfer window. It's not yet known where he will end up, of course, particularly as other members of Europe's elite are said to have joined the chase. What is clear, though, is that the man that makes Diniz's team tick is almost certain to move on during the winter window.

Helping Fluminense win a first Libertadores would mean departing with the best wishes and gratitude of everyone connected with the club for agreeing to stay for those extra few months.

They say everything happens for a reason - Marcelo would likely agree. After leaving Real Madrid a legend last year, the left-back endured such a difficult spell with Olympiacos that he felt compelled to cancel his contract after just five months in Greece.

However, in February, he was given the chance to go home. "It's difficult to express what this moment means to me," he said after rejoining Fluminense 16 years after leaving. "I've been dreaming of returning to my origins, to the team that trained me and taught me what I know about football."

Since then, Marcelo has been teaching his team-mates everything he knows about winning major trophies, with the Brazilian now on the verge of becoming only the 15th man in history to win both the Champions League and the Copa Libertadores.

"I don't think of myself as a renowned player who has lots of titles," he insisted. "What I did in the past has been and gone. I just always think about the now, and now I’m enjoying one of the best moments of my life, playing a final with Fluminense."

Marcelo may already have plenty of silverware in his trophy cabinet, but few football fans would begrudge one of the modern game's greatest defenders a fairy-tale finish at Fluminense.

The fact that the final is being played at the Maracana is obviously an advantage for Fluminense. However, those expecting a partisan atmosphere in and around the stadium might be in for a surprise, as more than 100,000 Boca Juniors fans are expected to arrive in Rio this weekend. Those that don't have tickets will descend upon the fan zone, meaning the 'visitors' won't want for support.

Valentin Barco adores the way in which Boca fans can make every match feel like a home game - but it's worth noting that they love him too. He's very much one of their own, after all, having come through the club's youth academy before making his senior bow at just 16 years of age.

He's still only 19, but Barco has continued to build on his early promise, and the versatile winger, who can also play at left-back, is now being linked with a number of massive clubs, chief among them Manchester City. Indeed, speculation is rife that the reigning European champions have already beaten off competition from Brighton to sign Barco for a fee in the region of £8 million ($9.75m).

If that is the case, the teenager should prove a bargain buy - as well as the potential solution to City's long-standing left-back problem, given Pep Guardiola would obviously adore a player that can defend as well as he attacks.

It's rare that a manager is simultaneously under pressure and on the verge of achieving legendary status - but that is the position both Diniz and Jorge Almiron find themselves in this weekend.

Why? Because despite their respective progressions to the Copa Libertadores final, neither Fluminense nor Boca Juniors are performing well in their local leagues. Flu's 1-0 loss at Bahia has left them eighth in the Brasileirao Serie A standings, while Boca are 10th in the Argentine Primera Division Group B, having taken just 11 points from 11 games.

Their exhausting exploits in the Libertadores have obviously had an adverse affect on their respective domestic performances. However, it's worth noting that while Fluminense have been flying in the Copa - no side has scored more goals than Diniz's free-flowing side (22) - Boca are heavily reliant on a backline that has been breached just five times.

Consequently, Almiron, who only took over in April, has been taking plenty of flak for his side's dour brand of football and somewhat fortuitous run to the Copa final, and there is no guarantee that he will be allowed to continue at La Bombonera if Boca are beaten in Brazil.

Diniz is also coming under scrutiny, too, not least because his spell as Brazil's caretaker coach is not going particularly well, with the Selecao held at home by Venezuela last month before being beaten in Uruguay.

However, the 49-year-old has a little more credit in the bank than Almiron. What's more, if he were to lead Fluminense to a first Copa triumph, it wouldn't just mean relief - or glory - it would also represent validation.

Right now, there is a debate raging among footballing tacticians over the respective merits of 'positionism' and 'relationism'. And if Guardiola is considered the finest exponent of the former, Diniz is, by his own admission, his philosophical antithesis.

That is not to say that the two coaches are polar opposites. Both champion the importance of possession and pressing; the difference lies in the approach to keeping a hold of the ball. Whereas Guardiola believes in creating space by deploying players in set positions - particularly out wide - Diniz's game plan is all about congesting certain areas of the field.

The goal is to play through teams with overloads and one-twos. It is high-risk, Futsal-style football and it can be punished by teams that specialise in rapid transitions. But it is truly beautiful to behold, a style of play that taps into the traditional, technical strengths of Brazilian players by encouraging constant interchanging of positions, and has thus evoked talk of a return of 'joga bonito'.

Which is why some supporters and pundits, like Romario, believe the Brazilian Football Federation (CBF) should ditch their plan to appoint Carlo Ancelotti as coach next year and give Diniz the job on a full-time basis, so that he has sufficient time to successfully implement what is a complex tactical strategy.

So, the final really isn't just about Fluminense or Boca Juniors. It's also about Diniz and a potentially pivotal moment in football history in terms of how the game is perceived - and played.