Ramires was one of the west Londoners' standout performers at Stamford Bridge.
"He helps things," Di Matteo said of Ramires. "I don't think he is the only one as we have a few goalscoring midfield players.
"I very much enjoyed the second goal he scored today.
"I think the scoreline was a bit harsh on Portsmouth, especially the way they were organised and defended.
"We are very pleased with it and we deserve a few goals as well."