Ole Gunnar Solskjaer insisted on Friday he is happy with his striking options for this season despite not signing a replacement for the departed Alexis Sanchez and Romelu Lukaku.
The Norwegian has just Anthony Martial, who will miss Saturday's trip to Southampton through injury, Marcus Rashford and 17-year-old Mason Greenwood to count on between now and January.
"Anthony and Marcus can carry our attacking threat," he said. "If not, we would have signed someone else or kept someone else.
"We believe in them. Both of them enjoy responsibility and enjoy the trust. It is give and take here - we trust them but they have to give us back.
"But they have shown me they are ready for that.
"If I did not believe in them, we would have signed someone else or kept someone else. We believe in them definitely."
It places great responsibility on a pair who have scored a combined 55 goals in the Premier League, as Greenwood is yet to score a senior goal, compared to Sanchez and Lukaku's record of 176 goals in England's top flight.
It also means there is no-one in United's squad who has scored more than 13 goals in a single Premier League campaign - the mark achieved by Paul Pogba from midfield last season.
Martial's absence due to a thigh injury at St Mary's means there could be an opportunity for Greenwood and Solskjaer is not concerned about having to hand him a first Premier League start.
"Mason is a natural footballer," he said. "He enjoys his time on the pitch and he comes alive when you get closer to the goal.
"In the finishing sessions, he is always the one who ends up in the last two. He always scores the goals.
"He has proper goalscorer's goals, but he also has to learn that scrappy bit inside the six-yard box and stick your head in where it hurts, but he has all the range of finishes."
Given Lukaku's exit and Martial's injury, there would surely have been an opportunity for Sanchez to face Southampton if he was still with United, but Solskjaer has no regrets about letting the Chilean leave for the season.
"I had a chat with him," said Solskjaer.
"For me, if I can't guarantee regular football for Alexis Sanchez, it's better for the two of us that he goes and plays in Italy and shows what we all know he is capable of doing. I could not guarantee him that here.
"I'm sure we will see Alexis back. We just hope he plays regular football for a year. Then he can find his form."
United's squad was further depleted as centre-back Chris Smalling also headed to Italy to join Roma on loan on Friday.
And Solskjaer's willingness to work with a small squad could be exposed in the coming months, particularly with long journeys ahead in the Europa League.
United will face Partizan Belgrade and Kazakhstan champions Astana, as well as Eredivisie side AZ Alkmaar in Europe's second-tier competition.
The pairing with Astana is particularly unfavourable as the trip to the Kazakh capital on November 28 will involve a round trip of over 7,000 miles before returning home to play Aston Villa in the Premier League on December 1.
