Last season's runners-up Boca Juniors were held by Bolivian hosts Jorge Wilstermann in Group G on Tuesday.
We assess the leading candidates for glory and the potential stars ahead of the start of the 2019 Copa Libertadores.
After the sale of Leandro Paredes to Paris Saint-Germain, Russian side Zenit have completed a deal to sign Wilmar Barrios.
After unsuccessful loans in Serie A, Benfica defender Lisandro Lopez has returned to Argentina with Boca Juniors.
Leonardo Balerdi has swapped Boca Juniors for Borussia Dortmund after signing a long-term deal at Signal Iduna Park.
Defender Leonardo Balerdi is set to complete a move to Borussia Dortmund, according to Boca Juniors president Daniel Angelici.
Nicolo Barella has been heavily linked with a move to Chelsea and Cagliari seemingly have a replacement lined up in Nahitan Nandez.
Lisandro Magallan has signed a four-and-a-half-year contract with Ajax after the Eredivisie giants agreed a transfer with Boca Juniors.
After upstaging bitter rivals Boca Juniors for a fourth Copa Libertadores crown, River Plate were drawn in Group A for the 2019 edition.
Five days after losing the Copa Libertadores final to River Plate, Boca Juniors have announced the departure of their coach.