Ole Gunnar Solskjaer has warned Manchester United are in danger of slipping even further down the Premier League unless his players improve and is resigned to missing out on the title again next season.
Solskjaer believes Watford, Everton and Leicester are among the teams with genuine ambitions to overtake United and climb into the top six over the next 12 months.
The United manager has argued his players have failed to reach their potential this season, with the club sixth in the Premier League and facing a huge job to finish in the top four and qualify for next season's Champions League.
Solskjaer, whose side are away to already-relegated basement club Huddersfield on Sunday, has acknowledged he has a significant job to revitalise the fortunes of a club who have not won the Premier League for six years.
And the former United striker has already written off their chances of finishing top next season.
Indeed his more pressing concern is to ensure the Old Trafford club, who headed into the penultimate round of league fixtures, a huge 27 points adrift of leaders and reigning champions Manchester City, do not fall further behind.
'Title not realistic'
The manager will attempt to strengthen his squad over the close season, but he still does not expect to be challenging the likes of City and Liverpool for title honours next term.
"It is not realistic," he said. "Of course, I'm an optimist but I don't think that's realistic, because the two teams now at the top of the table they are far ahead of the chasing pack.
"We have to make sure that we are getting closer and moving that way up the table and not looking over the shoulders because there are big clubs, good clubs wanting to chase that top six.
"You've got Leicester, Everton, Watford, probably Newcastle, you've got clubs that want to chase us. We have to make sure that we are ones who chase those ahead of us.
"You don't suddenly catch 27 points in one season, you've got to take it gradually," he explained.
"Hopefully we can produce better performances and they (City and Liverpool) can produce worse and we'll get closer."
A number of players are set to leave Old Trafford at the end of the season, including captain Antonio Valencia, while midfielder Ander Herrera and forward Juan Mata are both out of contract.
Meanwhile intense speculation surrounds the futures of midfielder Paul Pogba as well as forwards Alexis Sanchez and Romelu Lukaku.
Solskjaer does not expect to make a significant number of signings, though, and will instead focus on improving his existing squad, with increased fitness a priority.
"We've got to get it right on the pitch with the ones we have; it's not just about signing players," he said.
"It's about making sure that the ones here get the maximum out of their potential, because we do have so many good players here, and that's my job, to work with them.
"At the moment, I'm responsible for the performances. I'm the one that should get that flak if there is some," added Solskjaer.
"The fitter you are the more you can do. It's a basic principle I've got. If you look at the stats over the last few years I don?t think anyone would be shocked or surprised by them. We're going to build on their fitness."
United have gathered just seven points from their past seven league matches, severely damaging their chances of qualifying for next season's Champions League.
The manager, who won 14 of his first 17 matches in charge at United after replacing Jose Mourinho in December, has made clear that performances have slipped since then, and that some of his players will, as a result, be on their way out of Old Trafford.
"You give people a chance, but sometimes, you?ve got to be ruthless and say: 'Sorry but you had your chance'. I'm not afraid to do that," Solskjaer insisted.