A goal up from the first leg of their quarter-final tie at the Gerland, the Bianconeri looked poised to coast into the last four when Andrea Pirlo broke the deadlock after just four minutes of play in Turin with a trademark free kick.
However, Jimmy Briand dragged Lyon right back into it with his 18th-minute header and Juve needed a deflected effort from Marchisio midway through the second half to finally break their French foes' game resistance.
"We absolutely knew that it would not be easy to reach the semi-finals," the midfielder told Sky Sport Italia.
"We started very well. Then, however, we suffered a little setback when they equalised.
"It's clear that my goal was a little lucky, but now we will go forward and fight right until the end with our intent to complete our objectives."
Star striker Carlos Tevez once again failed to find the net for Juve in Europe this season, meaning it is still five years since the Argentine netted in continental competition.
However, Marchisio insisted that the Argentine, who had a goal disallowed for offside, had played his part in the Old Lady's progression to the semi-finals.
"The important thing is that the team wins," the Italy international mused. "In these cases, it's not necessary to focus on individuals.
"Carlos is a great champion who helps the team greatly even when he doesn't score. His presence this season has helped us to grow in so many ways."