A second-half strike from Premier League debutant Matthew Longstaff at St. James’ Park condemned Manchester United to their third defeat of the season and they now sit just two points clear of the relegation zone.
The defeat at Newcastle means Manchester United are winless in 11 consecutive away matches.
This is Manchester United’s worst start to a season since 1989-90 and they have not scored more than one goal since a 4-0 win against Chelsea in August.
The Norwegian took over Manchester United last season on an interim basis from Jose Mourinho before he was appointed permanently on a three-year contract in March.
Solskjaer believes their top four ambition hangs in the balance after accumulating just nine points out of a possible 24.
"We've given ourselves a big, big uphill challenge to get among the top four but it's tight and we need to get a run together," he said after the 1-0 defeat at Newcastle.
He added: “it will take however long it will have to take. It's a journey we've started on and the culture is getting there. I can't give you any time but we're getting there.
"We've come together and discussed the direction we're going. If you only work on sunny days, you'll never get to your destination. We'll have these days, but we know where we want to get to”.
After the international break, Manchester United face Liverpool for what could be another difficult test.