Atlanta United’s Ezequiel Barco will miss the start of training camp and, depending upon how long it takes him to return, may miss the team’s first two Champions League games because of tendinitis in his right knee. The team said the midfielder will miss three to four weeks.

Barco suffered a setback while with the Argentine U-20 team on Wednesday. Atlanta United released the diagnosis and prognosis of the injury on Thursday. Barco will return to Atlanta to begin rehabilitation.

Atlanta United, the defending MLS champs, will start training camp on Jan. 14. Its first two Champions Leagues games are Feb. 21 in Costa Rica at Herediano and Feb. 28 at Kennesaw State in the return leg.

Barco, 19, is one of Atlanta United’s Designated Players.

Barco is expected to play a big role for the team this season with the expected pending sale of Miguel Almiron.

Atlanta United acquired Barco before the 2018 season for a reported $15 million from Independiente in Argentina. He scored four goals and had three assists last season and was named to the MLS All-Star game.

He arrived in the middle of training camp last season. He was in line to start the season-opening game at Houston before sustaining an injury in the days before the game. The injury forced him to miss the first five games. He made his debut as a sub on April 15 in a 2-2 draw against NYCFC.