By NESTOR F. SEBASTIAN

South America will see its Copa Libertadores finalists determined this week when the second legs of the semifinals are sorted out with Club Nacional of Montevideo, Uruguay hosting Argentina's Estudiantes de la Plata in the first match-up tonight while tomorrow's all-Brazilian affair has Gremio welcoming Cruzeiro.

All four semifinalists aren't strangers to reaching the deep pools of competition in this tournament with Nacional and Estudiantes boasting three titles each while the Brazilians have won it twice apiece. Whoever wins the 2009 edition will still fall short of catching up to seven-time champs Independiente of Argentina.

Out of the four semifinalists, Cruzeiro looks like they have the easiest path to the final, nursing a 3-1 lead in the series while Estudiantes hold a narrow 1-0 edge.

Here is a preview of this week's 2nd semifinal legs:

NACIONAL v. ESTUDIANTES DE LA PLATA, Tonight 8:15pm ET

About 200 Estudiantes supporters crossed the Rio de Plata, or River Plate, into Uruguay for the impossible mission of obtaining tickets for tonight's second leg. Unfortunately, the hinchas, or fans, may have to watch tonight's crucial match at a local pub due to a row over distribution of visitors' tickets by each team's respective administrators, who deemed it too dangerous to allow supporters to trek into one another's cities. Estudiantes' 1-0 first-leg victory was played in front of a partisan crowd without the assistance of any Nacional fans.

With the slight lead over the Uruguayans, the Argentines have a tough task for tonight at the intimidating and historic Estadio Centenario where they will seek to topple the home team without the services of their influential captain, Juan Sebastian Veron, who picked up a calf injury in the first leg and is listed as doubtful. Matias Sanchez appears to be the man to replace him.

For Nacional, 20-year-old winger Nicolas Lodeiro is nursing an ankle knock but should be ready to come off of the bench unless manager Gerardo Pelusso has something up his sleeve and puts the young, dynamic player in the starting 11.

Nacional goalkeeper Rodrigo Munoz had a stellar match in the first leg, making some key saves to keep the series tight and is calling on his backline to stifle the Argentine attack, knowing that a Veron-less midfield could be taken advantage of.

GREMIO v. CRUZEIRO, Tomorrow 8:50pm ET

Cruzeiro is 45 minutes away of contending for a third title and knows it has to maintain a comfortable 3-1 lead albeit in front of a raucous Gremio crowd that will no doubt be voicing its disapproval of having one of its icons be accused of racism.

Former Argentine international Maxi Lopez allegedly called Cruzeiro defensive midfielder Elicarlos a monkey but the Gremio striker denies those claims.

Lopez and fellow compatriot German Herrera look like they will be the tandem up front for Paulo Autuori's side with Alex Mineiro on the bench because of lack of form in his recent matches.

Meanwhile, Cruzeiro will have a key piece back for tomorrow's match with Ramires returning from international duty following Brazil's Confederations Cup win over the U.S. over the weekend. It also appears that Thiago Ribeiro will be fine for tomorrow for Cruzeiro's attack after shaking off a minor knock that could've prevented him from playing. Gerson Magrao could also be back in the starting 11 after recuperating from injury.

In any case, the match has been labeled high-risk with security boosting its presence in the stadium, a norm for most South American continental matches, especially in Brazil.

What do you think about the semifinals? Will you be watching this final four? Who will win the whole thing? What player sticks out for an eventual transfer overseas? Share your thoughts below.