Chicharito scored both goals for ManU's in its 2-1 victory over Olympique Marseille on Tuesday. The team advanced to the quarterfinals for the fifth consecutive season.
At Old Trafford, Hernández put Man U ahead five minutes into the match after latching onto Wayne Rooney's cross.
The Mexico striker got the 15th goal of his debut season for United in the 75th minute. He netted from close range after Ryan Giggs squared the ball into the penalty area having received the ball from substitute Antonio Valencia.
"Hernández's pace and movement is helping us — he is real handful," United manager Alex Ferguson said. "Wayne is enjoying the freedom behind Hernández and is in really good form at the moment."
The three-time European champions clung on after Wes Brown headed into his own goal in the 83rd from Lucho González's corner while under pressure from Marseille defender Gabriel Heinze.
"Our game plan was to attack them first half and to get a goal or two up," Rooney said. "We managed to get one and we held on. We were unfortunate to concede the goal."
Marseille missed early opportunities to cancel out Hernández's opener, with striker Andre-Pierre Gignac shooting over and Souleymane Diawara heading wide when unmarked six yards from goal.
"My team have young players but after they have done well — and we had good opportunities — we don't score," Marseille coach Didier Deschamps said.
The only downside for United was that defender John O'Shea and his replacement Rafael both came off with suspected hamstring injuries.
"The balance of the team was affected with two defenders coming off," Ferguson said. "There was a lack of experience in the team and that could have cost us, but we hung on."
Real Madrid, meanwhile, will find out on Wednesday if Ronaldo will be able to go. Ronaldo injured his leg earlier this month.
"I'm not a doctor nor a player. After the treatment, we will decide," said Real Madrid coach José Mourinho.
Based on reporting by The Associated Press.