The Belgian striker only signed on loan in midweek but made an immediate impact within minutes of coming off the bench late on. He turned sharply to fire a shot which Fulham keeper Sergio Rico could only parry to Schlupp.
He admitted he had only met his new team mates for the first time hours earlier.
"I met my team mates today," he said. "I feel good to be here but I need to train with the team. It's a good start."
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The day had begun badly for Claudio Ranieri's side when Cyrus Christie needlessly handled the ball in the area as he challenged Christian Benteke on 25 minutes.
Luka Milivojevic duly put away the penalty, which was only Palace's seventh home goal of the season, and they almost got another moments later when Benteke's scissor kick thundered off the crossbar.
Fulham's Rico was by far the busier keeper and did well to beat away a deflected shot off Denis Odoi as Palace made light of the absence of suspended winger Wilfried Zaha.
Fulham remain the only Premier League side without an away win this season and are now seven points adrift of 17th-placed Burnley.
Fulham manager Claudio Ranieri said: "We were in trouble from the beginning but we will continue to be positive, be strong. It's important to be optimistic. We have a target in our mind."
(Reporting by Neil Robinson, editing by Pritha Sarkar)
