Cottagers boss Jol revealed he had agreed the 35-year-old Greece midfielder would only play for an hour of this afternoon's third-round clash at Craven Cottage.
But, with Fulham heading for an embarrassing 1-0 defeat in front of their own fans, Jol kept "warrior" Karagounis on the pitch and was rewarded with a late equaliser that set up a replay at Bloomfield Road.
"He's been in the team now over the last three games and I told him he could play 60 minutes today because he played the other games," Jol said of Karagounis, who signed on a free transfer back in September.
"I had to leave him on and I think he's not only a legend in his country, but he's a warrior for us.
"Of course, we had him outside of the transfer window but I was very happy that he came here and he showed that today.
"Because, that is what you need. That is what we had, for example, with Clint Dempsey."
Today's amazing half-volley was Karagounis' first goal in English football but Jol revealed he had seen the midfielder net similar efforts during his stellar career with Inter Milan, Benfica and Panathinaikos.
"If you've seen him on youtube, he probably did it eight or nine times before, and he's capable of doing that," Jol said.
He added of Karagounis: "I knew that he could force the issue, Karagounis, and he did.
"He's a character, he's a personality.
"So, although he was probably knackered, he scored the goal, and that is what you get with Giorgio."