The 22-year old scored his second league goal for the Union in five starts since returning home from Europe to help his club to a 2-0 away win over Seattle Sounders, enabling them to go top of the Eastern Conference table.
Adu finished brilliantly in the 60th minute after a clever run from Gabriel Farfan to open the scoring for the Union and he was grateful for the contribution of his teammate.
"That goal was all Gabe - it was just great work down the line," said Adu. "As a professional player we are taught to always go to the near post when the ball is down the line, to try to get in front of the defender. Lo and behold, the ball popped up right where I was.
"I was falling down and I had to concentrate on getting a good foot on it.
"The only place I could hit it was going up, trying to hit the ball to the roof of the net. I knew Kasey [Keller] was there but when you're falling down you want to hit the ball as hard as you can."