Berbatov joined the Cottagers from United at the end of the summer transfer window and this will be the first time since that he has gone up against his former employers.
But Jol says there is no talk of revenge for the Bulgaria international, who had fallen some way down the pecking order at Old Trafford and has scored seven goals in 19 Premier League outings since his move.
"I don't want to put pressure on him," Jol said. "Of course if he was playing for 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.
"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.
"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.
"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.
"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. For him the most important thing is that he can play football, he loves to play football."