"It's a big disappointment for us as we defended quite well," Di Matteo said of Swansea's late leveller. "They didn't create much."
"It was a quality goal they scored and it's a shame as we were so close to getting a win away from home.
"I think mentally and physically it's been very demanding playing two games against United [in a week]."
Following the recent controversy between the club and Mark Clattenburg, Di Matteo was asked about Friend's performance and he was full of praise for the official.
"I thought he was terrific. The referee had a fantastic game today," he said. "He let the game play, he was very good and I told him so after the game."