That is according to eight-time Olympic Gold medalist and Manchester United super-fan Usain Bolt.
The Red Devils take on Basel next week in their first Champions League match since being knocked out at the group stages in the 2015/16 season.
The club spent almost £150m on Romelu Lukaku, Nemanja Matic and Victor Lindelof over the summer, and re-signed Zlatan Ibrahimovic on a one-year deal.
But Jamaican athlete Bolt believes the new additions will still fall short in Europe's biggest competition.
“The Champions League is going to be hard, you know what I mean,” Bolt told ESPN.
“I think we’re missing a few vital (players), I think we need maybe one more striker, maybe a stronger defence and then we will be fine. One striker, one defender.”
Striker Ibrahimovic has been out since April after suffering a knee injury against Anderlecht in the Europa League.
He recently signed a new contract with the club after initially leaving in the summer.
And Bolt is looking forward to seeing the 35-year-old back in action for United.
“For sure Zlatan will be good but because he’s starting so late, because I think they said he’s not going to start playing until January, he’s not going to be in shape," Bolt added.
“It takes time to get into playing football, so it’s going to be tricky.
“The teams looks good but anything is possible, right?”
As well as facing Basel, United will take on Russian outfit CSKA Moscow and Portuguese champions Benfica in their qualifying group.
