Goals from Juan Mata, Frank Lampard, and a double from the Brazil international helped the Stamford Bridge club through to the fourth round, and Di Matteo was pleased with the showing.
“I thought it was a very good all-round performance,” Di Matteo told Sky Sports.
“Portsmouth made it very hard, especially in the first 45 minutes, and it is always difficult to break an opponent down and find a space with so many players.
“It was just a matter of scoring the first goal and we were always confident we were going to be able to do that.
“In the second half we got further forward and secured the win. I think it was a matter of finding the spaces and keeping possession.
“We knew the chances would come and that is exactly what happened in the second half,” he continued.
The former Blues midfielder was especially impressed with Ramires’ performance, and hailed the South American after the victory.
“He helps things. I don’t think he is the only one as we have a few goal-scoring 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,” the Italian coach concluded.
Chelsea will now take on either MK Dons or QPR in the next round.
By Gareth McKnight