The Frenchman struck three minutes into the second half but Chelsea had some nervous moments in the closing stages as Porto pushed hard for an equaliser before having Fernando sent off in injury time for a second caution.
With Atletico Madrid being held to a goalless home draw by APOEL Nicosia in the other Group D game, Chelsea manager Carlo Ancelotti was more than content.
"We couldn't hold on to the ball in the second half and could not control the game but Porto are a good side," the Italian told reporters.
"You can't always play your best and sometimes you have to win when you are below your best, that's an important characteristic for a team."
The last time Chelsea were in European action here, their hearts were broken by Barcelona's last-gasp equaliser in the second leg of last season's semi-final.
Chelsea could not find the second goal and memories of Andres Iniesta's injury-time strike for Barcelona began to emerge as some sloppy play offered the visitors too many sights of goal.
Having reached the semi-finals five times in the last six campaigns, Ancelotti's target is to make this the season Chelsea finally get over the line.
Porto coach Jesualdo Ferreira was not writing off his team's chances of progressing either.
"I think we should look at that game in a positive way," he said. "In the second half we controlled the game for long periods, we had a lot of shots and I think we were unlucky not to score.
"It's just the first game and we are still in a good position in the group. The door is still open."
