The Red Devils ended the Premier League season with a disappointing 2-0 loss to relegated Cardiff City at Old Trafford.
Solskjaer opted to hand Greenwood his first Premier League start alongside Marcus Rashford and Jesse Lingard for the visit of the Bluebirds.
The 17-year-old had seven shots on goal but the exciting youth prospect was unable to convert a chance to score a vital goal for the home side.
Greenwood made 21 sprints during the Premier League clash, which was more than any other Manchester United player on Sunday afternoon.
Only Lingard and Paul Pogba touched the ball more times than Greenwood, who also completed three dribbles and won three tackles.
Speaking at his post-match media conference on a day of few positives for the Manchester United boss, Solskjaer singled out Greenwood’s performance for praise.
“It’s so disappointing again, but then again the facts and reality are we created chances,” Solskjaer said.
“Mason was absolutely brilliant, got the crowd going, got the players going, but that’s a 17-year-old making his full debut and he’s the bright light.”
Solskjaer added: “He was our best player by a mile. He came into the team with a lack of confidence and you can see that has take a total. Not surprised by his performance, we know he is capable of that.”
Greenwood was named the Manchester United young player of the year earlier this month following his excellent performances at youth level this term.
The striker made his competitive debut as a 87th minute substitute for Ashley Young in a 3–1 win against Paris Saint Germain in the Champions League back in March.
Greenwood is the second youngest player to represent the club in a European competition and the youngest ever in the Champions League era at 17 years and 156 days.
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