The Brazilian playmaker expressed his disappointment after being selected on the bench against Corinthians, but Benitez insists there is no rift with the player.
"Oscar is fine. He's a very good professional. We don't have any issue with him," he said.
"I try to manage players, especially in his position because we have Eden Hazard and Juan Mata, who can do more or less the same job.
"It's difficult for them but it's good for me because I have different problems. There are no issues or problems.
"Oscar will have a lot of time on the pitch and I'm sure he'll be a great player for the club.
"Oscar's not happy because he's not playing and that's fantastic. There would be a problem if it was the opposite."
Leeds will be Benitez's eighth game in charge since taking over 25 days ago, a hectic schedule that continues with Christmas fixtures against Aston Villa, Norwich, Everton and QPR.
"We have to win every competition if we can. We have rivalry with Leeds and we have one less competition to win after losing on Sunday," Benitez said.
"We can't just call it another game, it's a very important match for us.
Benitez, who believes the Blues remain in the Premier League title race despite trailing leaders City by 13 points, predicts a change in fortunes soon.
"It's easier to lose in big games because you play against better teams. Normally in finals the other teams are good too," he said.
"It's just a question of time until we start winning games in a row. We are progressing and are going in the right direction, but we need to be more consistent."
Benitez admits he is in daily discussions with technical director Michael Emenalo over potential transfer activity for January.
"Hopefully we have two or three days after this game where we'll have plenty of time to talk about names," he said.
"There's no formal meeting because we can chat every day. Michael is watching the training session and we talk every day -- about players and how the team is doing.
"I know what Michael likes and he knows what I like and we come to an agreement."
Chelsea have been stretched by the loss of John Obi Mikel, Gary Cahill and Ramires to suspension and while striker Daniel Sturridge may return from a hamstring injury against Leeds, John Terry is still out with a knee problem.
The outlook on Terry is concerning with Benitez reluctant to offer a return date for Chelsea's captain.
Frank Lampard will start at Elland Road, but Benitez was non-committal over his future with the England midfielder considering his options for the January transfer window.
"Frank is fully committed in every training session and every game. He's an important player for us but I can't say too much about what he feels or doesn't feel. He's doing well and I'm happy about his attitude."
3Leeds v Chelsea, Sky Sports 1, KO 7.45