The European champions are currently at the heart of a storm after accusing Mark Clattenburg of racially abusing John Obi Mikel.
And it had been reported Di Matteo was worried the case would see Chelsea suffer at the hands of match officials.
But after the 1-1 result at Swansea, the Italian told Sky Sports: "I always said I don't fear that. I have faith in the officials. Today was a very good performance by them."
Asked specifically about Friend, Di Matteo said: "I thought he was terrific. The referee had a fantastic game today and let the game play. I told him after the game."
Chelsea surrendered top spot in the Premier League to Manchester United as a consequence of the draw with Swansea, who equalised Victor Moses' opener through Pablo Hernandez's late strike, and Di Matteo was disappointed.
But Chelsea have played three games in less than a week following last Sunday's controversial defeat by United, when the accusation against Clattenburg took place, before gaining revenge against Sir Alex Ferguson's team after extra time in the Capital One Cup.
And Di Matteo said: "Mentally and physically it has been very demanding, playing two games against Manchester United and also the extra time.
"But the players responded with a lot of commitment today and we nearly won."