The Chilean government said on Tuesday the players would not be exempted from measures to counter the coronavirus, which has claimed 4,000 lives globally.
Chris Smalling signed for AS Roma on a season-long loan deal a few days after Alexis Sanchez signed for Inter Milan on loan.
Alexis Sanchez will reunite with Romelu Lukaku at Inter Milan, who left Manchester United in the summer transfer window.
Both United and Inter reached an agreement that will see the English Premier League pay a portion of the Chilean's wages.
Chile beat Colombia 5-4 on penalties after the game ended goalless after regulation time.
Alexis Sanchez scored the winner in the second half, despite facing an ankle-injury to lead Chile to the quarterfinals of the competition.
The victory moved Chile to the top of Group C along with Uruguay, which opened with a 4-0 win over Ecuador on Sunday.
There was no place for Manchester City goalkeeper and former Chile captain Claudio Bravo, who was left out despite having returned to training following a ruptured Achilles tendon.
Sanchez was forced to limp out of United's dramatic 3-2 win at home to Southampton on Saturday, and Onate said he had suffered "medial ligament distension" in his right knee.
The forward's fifth goal in 33 appearances since leaving Arsenal a year ago set United on its way to a 3-1 victory on Friday that booked a place in the fifth round of the FA Cup.
Sanchez has so far had a disappointing season at home, scoring just one goal in the Premier League in 10 appearances.
Sanchez wasn't among the United squad heading across the Atlantic because there was an issue with his visa after the forward accepted a 16-month suspended sentence in Spain over a tax issue.
Coming off a superb win against the league leaders in the previous weekend, Mourinho's Reds faltered against a determined West Brom, who had nothing to lose.
Not even a 2-0 victory over Brighton was enough to mellow United manager Jose Mourinho, whose joy at beating Liverpool last weekend in the league was wiped out by a Champions League exit to Sevilla.
Former United skipper Vidic feels that Sanchez's quality and experience can be the difference in United's chance in chase fo trophies.
The winger refused to sign a new deal with Arsenal and was highly speculated to reunite with his former boss Pep Guardiola in Manchester City.
The winger has made a bright start as he scored on his debut and Sanchez has set a new record on social media as the deal announcement post was 'the biggest United post on Instagram'.
The Chile forward created goals for striker Marcus Rashford and midfielder Ander Herrera before coming off with around 20 minutes remaining.
Sanchez, who joined United over neighbor and Premier League leader Manchester City, said he was "thrilled to be joining the biggest club in the world."
A direct swap deal with no fee included, the former Borussia Dortmund player who spent two seasons under Mourinho will now sport the Gunner's crest, taking Sanchez's position.
Top News
Latest News
