Ronaldo cancelled out Josip Ilicic’s opener to leave the two teams level at the interval of the Champions League contest.
Ronaldo, a mere passenger in the game so far, held his arms outstretched in frustration as though he had expected a pass.
Lingard replaced goalscorer Ronaldo on the 71st minute as Ole Gunnar Solskjaer looked for a winning goal.
Pochettino stated that it took a while to process that the club had signed the six-time Ballon d’Or winner.
Ronaldo’s last Champions League match for United was the 2009 final loss to Barcelona in Rome
They will now face the winners of the other semi-final between Chelsea and Real Madrid in Istanbul later this month.
The tie is delicately poised following a 1-1 draw at the Estadio Alfredo Di Stefano last week.
They created enough chances to have clawed back the two-goal deficit but goalkeeper Thibaut Courtois was hardly extended.
City responded in the second half with a penalty from Riyad Mahrez and a fine effort from Phil Foden to win 2-1.
The Black and Yellow were minutes away from claiming a 1-1 draw from the first leg at the Etihad.