Victory put United top of Group C from Benfica, who visit Old Trafford next later this month.
It puts the Red Devils in pole position to qualify for the knockout stage.
"We've won the game and it has put us in the position where if we win that we've won the group so that is the incentive for us," said Ferguson.
"Given the history between both clubs (us and Benfica) it should be a good night, a good atmosphere, a really big game and we can look forward to that one.
The only downside was an injury to Michael Owen, who lasted just 10 minutes before limping off.
"It's a blow for the lad. He's done a thigh muscle and it's a complete freak," said the United boss.
"I feel for him. It's difficult to say how long-term it is."