The Portuguese midfielder believes the duo would take the Red Devils to another level as they prepare to fight for the Premier League title next season.
Ole Gunnar Solskjaer has assembled a strong squad over the past two seasons, with United on course to finish second in the Premier League and win the Europa League this campaign.
But there are always areas that can be improved, and Solskjaer has made it clear in the past that he is always looking for ways to strengthen his team.
Fernandes is currently negotiating a new contract with Man United, worth around £ 200,000 per week.
And according to The Sun, the midfielder would like to see Solskjaer bring in a new center-back and defensive midfielder this summer before signing on the dotted line.
Fernandes believes a ball-playing defender and a solid midfielder behind him would give him more creative freedom to move forward.
The two obvious candidates for United to sign are Jules Kounde and Declan Rice.
Both players have been on United’s radar for some time, with the Red Devils previously linked with a £ 80million transfer to Frenchman Kounde.
The duo would love to move to Old Trafford, but Rice in particular may find some resistance from her club West Ham.
Solskjaer is likely to continue turning between David de Gea and Dean Henderson on goal next season, while Aaron-Wan Bissaka, Luke Shaw and Harry Maguire and shoo-ins in defense.
Kounde would fit straight into the back four if signed.
In midfield, Solskjaer has more options, but Paul Pogba and Fernandes are the mainstays when in good shape and would likely perform well alongside someone like Rice.
Up and again, Solskjaer can turn.
But Edinson Cavani, who recently signed a one-year extension to stay at Old Trafford, is expected to lead the line next season.
He will be joined by Marcus Rashford and Mason Greenwood, as well as Anthony Martial, Amad Diallo and Daniel James in rotation.