Dimitar Berbatov believes united need two defensive signings as well as Jadon Sancho in this summer's transfer window.
The former Manchester United striker has named right-back and centre-back as two areas Ole Gunnar Solskjaer should look to improve in if he is to build on a promising campaign.
Manchester United have made Dortmund winger Sancho their top priority this summer, with negotiations continuing between the two clubs.
Bima Sport understands United are considering another attacking midfield signing and a left-sided centre-back.
But Berbatov has his own transfer advice for Ole as he highlighted in his Betfair blog what United need to mount a Premier League title challenge.
"They need a centre-back, maybe a right back also as Aaron Wan-Bissaka is the only option at the moment," said the Bulgarian.
"It looks like Alexis Sanchez might stay at Inter permanently, which would make room for Jadon Sancho to go to United from Dortmund, and it would be a very interesting transfer.
"Every season is different and has its unique ups and downs, the teams you expect don't always end up doing well, but with United you always expect them to be title contenders, especially if they make some signings."
