Sir Alex Ferguson’s men remained unbeaten at home in the group stage of the tournament, conceding just one goal in the process, and the 20 games they have played in all competitions at Old Trafford this season have yielded 17 victories.
But the French champions have taken heart from holding United to a goalless draw in the first leg at the Stade Vélodrome last month.
Following the first leg, boss Didier Deschamps stated that the current Red Devils line-up lacked some of the “fantasy” of previous generations, and Gonzalez insists he and his team-mates are inspired, not intimidated, by the task facing them.
"We go to Manchester without fear and ready to beat United. They may look upon Old Trafford as a bunker but the challenge of beating them there is very attractive to us," the 30-year-old Argentine said in The Sun.
"Clearly United are not the invincible team of other years."
With the tie delicately poised, Gonzalez believes the team who goes out and seizes the initiative will have a potentially decisive advantage, and revealed that his manager has stressed the importance of scoring first to his players.
"Being at 0-0 from the first leg is a very dangerous situation for them because one goal from us and they must pull out all the stops,” he said.
"Our coach Didier Deschamps has ordered us to do this to change the whole panorama of the tie.
"Marseille certainly won't be ultra-defensive, I think that would be a disaster for us."
With his side set to take the game to their hosts, Gonzalez fancies his chances of breaching the United back-line, based on what he has seen of the Premier League leaders this season.
"After watching their cup win over Arsenal, I'm sure I can score against their defence," he said.
"I've waited a long time for this opportunity and want to experience the sensation of knocking Manchester United out of the Champions League."
By Liam Twomey
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