Argentina's Lionel Messi and Portugal's Cristiano Ronaldo are both set to play for their countries for the first time since the 2018 World Cup in Russia.
Messi is due to start Friday's friendly for Argentina against Venezuela in Madrid, with Ronaldo in the squad for Portugal's opening Euro 2020 qualifier at home against the Ukraine in Lisbon.
Both men have missed six international matches since the World Cup.
Portugal reached this summer's Nations League semi-finals without Ronaldo.
The 34-year-old has scored 85 goals in 154 international games and could also play in Portugal's game in Serbia on 25 March.
Portugal defender Joao Cancelo, Ronaldo's team-mate at Juventus, was delighted to have him back in the national squad.