However, he was then substituted by Solskjaer after Young Boys equalised.
United then sensationally conceded a 95th-minute winner to begin their European campaign with a disappointing loss.
However, Ronaldo noticeably reacted well to being taken off for Jesse Lingard, whose error subsequently led to Young Boys’ winner.
The 36-year-old was pictured barking out instructions on the touchline alongside Solskjaer in a bid to help his side to a maiden Champions League win of the season.
Ronaldo’s shouts were not able to prevent a late winner but it proves that the former Real Madrid star is a leader.
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But Solskjaer and the Old Trafford transfer hierarchy stepped in and Ronaldo’s return was agreed in principle within 24 hours of City’s interest.
The paperwork for the deal was completed four days later.
Solskjaer handed Ronaldo a start ahead of his first game and the striker opened the scoring.
Mason Greenwood’s long-range effort was spilled by Freddie Woodman and Ronaldo tapped it in.
He then scored his 120th goal in a United shirt, hammering a powerful effort under Woodman after Javier Manquillo had equalised.
Bruno Fernandes and Lingard added further goals.