Manchester United face a "difficult season" unless they strengthen their squad before Thursday's transfer deadline, says manager Jose Mourinho.
The Red Devils ended their pre-season campaign with a 1-0 defeat at German champions Bayern Munich on Sunday.
Javi Martinez headed home a second-half winner to give Bayern victory in a match they dominated.
"My CEO knows what I want and I still have a few days to wait and see what happens," Mourinho said on MUTV.
"The other clubs who compete with us are really strong and already have fantastic teams. Or they are investing massively like Liverpool, who are buying everything and everybody.
"If we don't make our team better it will be a difficult season for us."
United have so far signed three players this summer - Brazil midfielder Fred for £47m, Portuguese defender Diogo Dalot and third-choice goalkeeper Lee Grant.
They open the Premier League season against Leicester City at Old Trafford on Friday.
United lack attacking intent
United ended their preparations for the new season in uninspiring fashion, struggling to threaten Manuel Neuer's goal.
Marcus Rashford's pace gave the hosts something to think about, but the Englishman was isolated for much of the game as the visitors failed to supply their forwards with any real service.
World Cup-winning midfielder Paul Pogba, Belgium striker Romelu Lukaku and England forward Jesse Lingard were among a number of players missing from United's pre-season fixtures.
And the return of some of those established stars will only enhance the team's attacking potential.
However, with speculation surrounding Anthony Martial's immediate future, and several others sitting out the club's entire pre-season, it is unclear whether United will be in a much stronger position when they open their domestic campaign against Leicester.
But Mourinho's pre-match comments suggest he is still looking for reinforcements.
Eric Bailly was forced off in the second half after a collision with Serge Gnabry, and central defence is an area the Portuguese is reportedly interested in strengthening, but it may be that Sunday's performance will emphasise a growing concern in the final third of the pitch.