The Eagles drew a step closer to the climax as goals from the Ghanaian and Max Meyer propelled them into the quarter-finals at The Keepmoat Stadium.
"I found a bit of space on the left side so I drove into space and before I knew it, I was in the box," Schlupp told his club's official website.
"I thought I'd get a good strike on it and see what happens and thankfully it went in.
"We scored two good goals and are through to the next round."
With the last-eight draw set for Monday, Schlupp is looking forward to an outcome that will better their chances of reaching the semis.
"We obviously knew if we got past this round, we'd be in a good position," he said.
"Of course this is a special tournament and hopefully with the luck of the draw, we might get a 'lesser' team - if that's what you want to call it - to have a better chance of getting through.
"But obviously any trip to Wembley is special and hopefully we can do that."
Schlupp's goal was his fifth effort in all competitions for Palace this season, having failed to find the back of the net in his first two seasons with the club.
The tally also stands as his highest in a single campaign since hitting six strikes for Leicester City in 2011-12.