Self-confessed Manchester City fan Manuel Pellegrini says he could not believe Manchester United lost 7-0 to Liverpool on Sunday.
Real Betis boss Pellegrini will lead his side against United in Thursday’s Europa League last-16 first leg at Old Trafford.
The 69-year-old Chilean spent three seasons in charge of City between 2013 and 2016.
“It really was unbelievable,” he said of United’s defeat at Anfield.
Pellegrini watched the first half of the game before he had to concentrate on his own side’s encounter with Real Madrid, which they drew 0-0.
“I missed the other six goals but I understood immediately what would happen,” he said.
“Because of the rivalry [with Liverpool] and this amount of goals, I knew it would not be easy for them.
“But I was not very sad about what happened. I am a Man City fan as well.”
Pellegrini won three of his six meetings with United as City boss, including a 3-0 triumph at Old Trafford in 2014.
His Betis side, who are fifth in La Liga, topped their Europa League group, while United reached the last 16 by beating Barcelona 4-3 on aggregate in the play-off round.
United’s last five European campaigns have ended with defeat to Spanish opposition – and they also lost to Real Sociedad in September in the group stage.
“I cannot know what they think but if Real Sociedad can do it, we can beat Manchester United also,” added Pellegrini.
United will be without midfielder Marcel Sabitzer and striker Anthony Martial for Thursday’s game.
Sabitzer came off the bench in Sunday’s defeat at Liverpool but has been ruled out of the European tie.
Martial has been out for over a month and is back in training but not yet ready to return to first-team action.
Midfielders Christian Eriksen and Donny van de Beek are long-term absentees.
“For the rest, everyone is available and we are ready for the game,” said United boss Erik ten Hag.
Real Betis are without star forward Nabil Fekir, who has been ruled out for the rest of the season with a knee injury.
