Velez Sarsfield are all that stand in the way of a third straight all-Brazilian Copa Libertadores final

There is only one chance of avoiding a third consecutive all-Brazilian final of the Copa Libertadores, and it seems a slender one. The first legs of the semifinals are played this week, featuring three Brazilian clubs -- the past two winners of the competition, who were also last year's finalists, plus the winner of the 2021 Copa Sudamericana -- and Velez Sarsfield, the team that occupies the 27th position in Argentina's first division, with one win in 16 rounds.

Velez, then, are taking a peashooter to a clash of the titans. They are the most under of underdogs as they prepare to host Flamengo of Rio in Wednesday's first leg, but they have performed miracles merely to have reached this stage; they lost two of their first three games in the competition and failed to win any of their first four. So why not aim higher still?

An incurable romantic could, after much mental striving, make a case for their chances. They can attack down the wings, with Lucas Janson cutting in from the left to good effect, and it is here that Flamengo's diamond midfield can leave the team vulnerable.

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Flamengo's strength lies in a dazzling collection of attacking talent. Everton Ribeiro and the Uruguayan Giorgian De Arrascaeta are a fine pair of attacking midfielders, while Gabriel Barbosa carries a left-footed threat and centre-forward Pedro is in a run of form rich enough to carry him into the Brazil squad. The club have played the front four ever since Portuguese coach Jorge Jesus arrived in the middle of 2019.

The price the club pays for such a bold approach is a constant search for defensive balance. Three years ago, Spanish centre-back Pablo Mari solved the problem by organising a high defensive line. He has never been adequately replaced since he returned to European football in January 2020, and the headache now emerges from the bout of hepatitis suffered by David Luiz. He had to be withdrawn at half-time in last week's domestic cup tie. In his absence, Flamengo were unable to build from the back, and invited more pressure on themselves. Their goal has led something of a charmed life in some recent away games, but their luck might be due a change on Wednesday.

Even if Velez can spring a surprise and build up a first-leg lead, it is not easy to see how they can defend against Flamengo a week later in the Maracana. True, they can take heart from keeping a pair of clean sheets in both second-round matches against River Plate -- they have already eliminated one giant, and have earned the right to dream -- but Flamengo are overwhelming favourites to reach their third final in four years.

And the most likely candidates to fill the other place in the final are Palmeiras, who beat Flamengo in last year's showpiece to become the first team in 20 years to retain the continental crown. The architect of this spell of success is Portuguese coach Abel Ferreira, who must now get past a team coached by Luiz Felipe Scolari, the only other boss to have taken Palmeiras to a Libertadores title, back in 1999.

Scolari is now in charge of Athletico Paranaense, stepping in after a disastrous start in which the team had failed to win or score in its three first games in the competition. In his wily, pragmatic way, Scolari has steered his counterattacking side over the line. The two previous knockout rounds seemed bound for penalties until Athletico struck with stoppage-time goals.

Athletico are a well-organised club with big ambitions. They have never won the Libertadores, losing in the 2005 final, but they are the reigning champions of the Copa Sudamericana. They need to be well run in order to compete with the giants. This obviously imposes some limitations, and means that a counterattacking style, marshalled by Fernandinho in midfield, is probably their best bet.

Palmeiras, meanwhile, look like a free-scoring side at first glance. No one can compete with the 35 goals they have scored in the competition -- even Flamengo trail this figure by nine goals -- but Palmeiras were drawn in an easy group, and Abel Ferreira's side, demolishers of the weak, tend to play things tight in the big game, with mobile, talented little striker Rony as an escape valve. Midfield powerhouse Danilo is suspended for both legs, while Gustavo Scarpa, vital for his left-footed set pieces, has to sit out Tuesday night's first match.

Will Scolari look to take advantage of these absences? A cautious struggle is more likely.