Berbatov, 31, moved to Craven Cottage in the summer after a four-year spell at United which saw the Bulgarian experience the highs and lows of a modern footballer.
After finishing as the Red Devils' top goalscorer the last time they took the Barclays Premier League title in 2011, Berbatov found himself well down the pecking order behind the likes of Robin van Persie, Javier Hernandez and Danny Welbeck.
Jol, who worked with Berbatov at Tottenham, moved to take him to Fulham before the end of the summer transfer window but will not challenge the player to show United what they have lost by letting the former Bayer Leverkusen man leave.
"I don't want to put pressure on him," Jol said. "Of course if he was playing for Man United it would be a bit easier for him but he is not playing for them any more, he plays for us."
"Hopefully he will do something nice, but for me it is important that he works for the team. We would love to go to the next round, even though we are playing against United."
Berbatov is likely to be the focal point of Fulham's attack on his first return to Old Trafford, but Jol is not telling his star name to try to prove a point.
"That would be unfair because he can't do it on his own," he said.
"If we get a good day there maybe we could end up with a surprise and you never know, hopefully he will come up with something out of the blue, but that is the same for all of my players."
Berbatov scored five goals in his first seven games this season but has found the net just twice since, and Jol admits the Bulgarian can find the football being played by the Cottagers frustrating at times.
"It was better probably the first couple of months when we scored a lot of goals and we had a settled team, but of course we had to change that," Jol added.
"The supply was probably not always great and he is not someone who can hide that and I talk to him all the time about these things and he wants to do well."
"Of course he has to do better on occasion, but eight times out of 10 he is our best player."
Much has been made of Berbatov's demeanour, but Jol is happy to have him around the club.
"He is a good professional, he is a bit within himself and is not someone who is noisy and talks a lot but as an example he tries to be a leader," he said.
"For him the most important thing is that he can play football, he loves to play football."
Jol has never beaten Sir Alex Ferguson in his managerial career but came close when Fulham lost 3-2 at Old Trafford in the league at the start of the season.
The Dutchman is hoping his side can recreate their display from that day and not sit back and let United come at them.
"Hopefully we can have possession and take more initiative in an away match because that is important," he said.
"If you have to defend in your half the whole time you give them more confidence and get put under pressure and they will create chances."