The Canada international added a goal from penalty in the Premier League 2 fixture, having also scored against Salford City in a friendly last month.
"It was good for me to get a goal and I was very pleased to get one," Millar told the club's website.
"It has been frustrating because I've hit the bar, hit the post, but hopefully now I can get some more goals. I was so happy to finally get my first goal of the season and I feel like I can really start to get going now.
"I thought it was a really good performance from the lads. We came out fast and flying and caused them a lot of problems.
"We know Chelsea like to play and we knew if we could get into them we would make it a tough game for them."