Mikel occupies the anchor role just in front of the defence and gets only rare chances to go for glory further forwards, evidenced by the fact he is still waiting to bag his first goal in 135 Premier League appearances for the Londoners.
The 25-year-old scored a rare goal at the weekend when he converted a penalty in Nigeria's 6-1 rout of Liberia as his side qualified for the African Nations Cup finals.
"Over the years he has been almost ever-present," Di Matteo told the club's website on Monday. "He was very important at the back end of last season and this season he has started in good form.
"We all make mistakes in games and I don't think he gets the credit for the work he does for the team."
Earlier this month, Di Matteo said: "I don't know why Mikel is underrated by the media or the fans. He is very rated by us in the group and it's a position where you're a bit of an unsung hero.
"You do the dirty work which is not recognised all the time because the goalscorers and more creative players get the recognition. But he is very important for our team."
