The Belgium international has made an underwhelming start to the Premier League season and Lukaku’s struggles are reflective of the team’s woes as a whole.
Lukaku has failed to score in his last eight games in all competitions for the 20-time English champions to continue to toil up front in Mourinho’s team.
The 25-year-old has scored four goals in the current campaign but the former Chelsea FC striker hasn’t found the back of the net since a 2-1 win at Watford on 15 September.
The £75m signing was particularly disappointing in Manchester United’s 1-0 loss to Serie A giants Juventus in the Champions League group stage on Tuesday night.
While Juventus defender Leonardo Bonucci and Giorgio Chiellini kept Lukaku at close quarters, the Manchester United striker failed to hold the ball up when his team-mates did find the striker with a pass.
Speaking to BT Sport after Manchester United’s 1-0 loss to Juventus at Old Trafford, Mourinho accepted that Lukaku is going through a difficult spell at the 20-time English champions.
“The player is a fantastic professional who wants to give everything for the team but I have to agree, his moment is not sweet,” said Mourinho.
“Not just for the goals he’s not scoring but his confidence, movement and touch. He is not linking the game well with the team. But he’s our striker, he’s a good striker and a striker we believe in.
“Could I play Rashford there? Then I don’t have a winger as we’re in this difficult [injury] situation. He’s a hard-working professional. One day the goal will arrive and the confidence will be back.”
Lukaku moved to Manchester United in a £75m deal from Everton in the 2017 summer transfer window despite having the opportunity to secure a return to Chelsea FC.
The Belgian’s arrival received a mixed reception but the forward went someway towards silencing his critics with a healthy return of 27 goals in 51 games in all competitions last term.
Manchester United will be hoping to return to winning ways when the Red Devils welcome Lukaku’s former club Everton to Old Trafford in their next Premier League game on Sunday afternoon.
The Red Devils battled to a 2-2 draw with Chelsea FC at Stamford Bridge in the Premier League last weekend after Anthony Martial’s quick-fire double cancelled out Antonio Rudiger’s opener before Ross Barkley netted an injury-time equaliser.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news