Gary Cahill then equalised for Chelsea and just when it looked like the game was going to end in a 2-2 draw, Fernando Torres scored a goal 10 minutes from time in a suspiciously offside position. Reading's late attempt to get a goal ended up with Hazard leading a counter attack and setting up Branislav Ivanovic for a late goal.
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Di Matteo said he had yet to see Torres' goal, which also allowed Branislav Ivanovic to kill off Reading on the break.
"I looked at the linesman straight away and he gave it straight away, so I can't comment," said Di Matteo, who was pleased to see his side go top of the Premier League for the first time since November 2010.
He said: "We are very pleased with six points after two games.
"I was very happy with the team performance for long periods of the game.
"We lost a bit our composure after Reading scored the equaliser and second goal, but we'd started off very well, with some great football, and finished off very strongly."
The positives included another standout performance from new signing Eden Hazard, who helped himself to two more assists to add to his pair at Wigan on Sunday.
Di Matteo said: "Hazard had an impact in our team.
"He's finding his feet very quickly, so that is pleasing for us."
The negatives were all too apparent, with Chelsea's defence looking anything but solid and captain John Terry enduring a particularly tough time.
"At 2-1 down, we were very offensive and maybe lost our balance a bit, because we were behind," said Di Matteo, the latest manager to be charged with making the Blues more adventurous.
"The balance was always going to be the key.
"It's all great and everyone wants to see a lot of flair play but, to win games, you need a good balance to it. That's going to be the challenge."
Di Matteo was confident David Luiz would be fit for Saturday's game with Newcastle after the defender missed tonight's match with a knee problem.
Luiz ruled himself out publicly on Twitter and Di Matteo revealed the club would deal with the potential breach of confidentiality "internally", likely meaning a warning.
Di Matteo refused to comment on reports Cesar Azpilicueta was on the brink of signing for Chelsea, while McDermott gave short shrift to suggestions Reading were trying to buy the right-back's Marseille team-mate, striker Jordan Ayew.
He said: "I heard that too as well. I don't think so..."