England international Rashford has scored 19 goals and supplied five assists in 31 appearances for United this season, making it the most prolific campaign of his career.
The 22-year-old has not featured since the 1-0 FA Cup third-round replay win over Wolves in January, having sustained a double stress fracture in his back.
With the Premier League not expected to restart until mid-June due to the coronavirus pandemic, Rashford may be fit enough to help United push for Champions League qualification.
Asked to name United's best player by the Guardian, Matic said: "We have a lot of young players, but they have maybe not reached their top yet, but Marcus Rashford has the ability to be one of the best players in the world in his position.
"He's still improving, but he has everything to reach that top level."
The stoppage in global football came as United were enjoying an 11-game unbeaten run that saw them keep nine clean sheets.
Their upturn in form came shortly after the signing of Bruno Fernandes from Sporting CP in a deal potentially worth £67.6million (€80m).
Fernandes has been involved in seven goals (three scored, four assisted) in his nine appearances and Matic was not expecting the Portugal international to have such an immediate impact.
"Because I follow the Portuguese league, I knew he was good – even though he played for Sporting!" said former Benfica midfielder Matic.
"But I'm very surprised he adapted so quickly to the Premier League. He brings us a lot of qualities, like the confidence he has on the pitch – he always knows what he wants to do with the ball."
Matic is confident United are heading in the right direction under manager Ole Gunnar Solskjaer.
He said: "Ole is a great manager. I think he has improved a lot since he came to United, and he is different now. I'm sure he has a great future here, and he will win us trophies."