The 21-year-old winger, who has been linked with Chelsea this month, scored the opener after 17 minutes at Elland Road.
"I don't have to worry about him anymore," Lampard said about Gordon. "You saw his worth to this club. Attitude amazing. I said from the day I joined the club that I want more goals from him. He has everything.
"Attitude, ability, speed and it was a great finish. We are playing games at the minute without an out-and-out striker. We need that output from our wingers. Now we have a striker for the next game and we get stronger.
"From where we were last season, in a real dogfight and needing to turn a lot around in terms of spirit. This season, for people to expect us to play beautiful football and fly up the table, but you have to build from the bottom.
"I know we have lost some games but we are hard to beat, not conceding. We maybe lose this game last year. Whether you play five or four, you get the discipline right. We will get braver and better on the ball and have a nice balance to us."