The Serbian, once accustomed to playing in a more advanced position, won a league title and a domestic cup at Benfica between 2011-2014 and revealed the time he spent in Lisbon had transformed him as a player.
"When I first came to Benfica, the manager Jorge Jesus told me I would be playing as a defensive midfielder," Matic, who has impressed since joining United from Chelsea during the close season, told the club's television channel (MUTV) on Tuesday.
"At the beginning, it was strange for me because I didn't know I could play that position but slowly, the manager explained to me how to do it.
"And after a lot of hard work, now, I am at Manchester United so I must have done the job well."
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The 29-year old Matic was sold to Benfica by Chelsea in 2011 and after he was bought back by the West London side three years later, he won two Premier League titles, an FA Cup and a League Cup.
After moving to United in July on a three-year contract for a reported fee of 40 million pounds ($53 million), Matic has quickly established himself as their midfield anchorman and drawn praise from manager Jose Mourinho, who also coached him at Chelsea.
United are second in the Premier League two points behind arch-rivals City and have made a good start in Europe's elite club competition, having won their opening two Group A games against CSKA Moscow and Basel.
A win at Benfica would put them on the verge of reaching the knockout stages.
Matic said Benfica, winners of a record 36 Portuguese league titles and successive European Cups in 1961 and 1962, were still very close to his heart.
"It's a special club, a club that I love," he said.
"At Benfica I learnt a lot about football and the pressure of playing for a big club, because they are one of the best clubs in Europe.
"I will support them for the rest of my life and they will have a special place in my heart, but in the Champions League I hope we can take points from them."
($1 = 0.7588 pounds)
(Writing by Zoran Milosavljevic; Editing by Toby Davis)
