"The boys didn't turn up in the first 20 minutes. They were very slow and they needed to be pumped and ready," he said.
"We also shouldn't have conceded the first two, it was bad defending and they were very poor goals to concede.
"But this result won't define our season. The best thing is for us to be positive and move on. We have quality in the team so I am not worried at the moment."
Cambridge took control early on in the game - taking the lead in the seventh minute when Szabo volleyed in after a cross from the right.
Five minutes later Szabo pounced again with his right foot from close range after Cambridge attacked once again down the right.
Just before half time Cambridge extended their lead when 15-year-old Tipping cut in from the left, played a delicate one-two with Callum MacCleod and slotted the ball inside the far post.
The result was sealed 10 minutes into the second half after MacCleod was brought down in the box and Chewins calmly tucked the ball to the right of the keeper.
Van der Lann was able to restore some pride for United shortly after, but it was too little too late.
Cambridge assistant coach Brett Clarke was happy with the result as his side moved to a point behind the second placed Matamata Swifts and six behind leaders Ngongotaha AFC, with a game in hand.
"It was one of our strongest performances so far this season, and Quest really stood out today. Such a young talent and he kept a very cool head," he said.
"I knew Rotorua would be very hard opposition because of some of their results so far, so I made sure the players were hungry from the off.
"We are looking at chasing down the top two because we want to win the league and get that promotion."
