The two sides played out an entertaining 2-2 draw at the Camp Nou last week.
Manchester United have won the most games(27) among club in Europe's big five leagues this season and head into the game in good form.
Ten Hag, who took charge of the club after leaving Ajax this summer, has overseen some impressive victories thus far but believes a new level of performance will be required to get the better of the La Liga leaders.
"When you face such big teams as Barcelona you have to play your best, otherwise you don't have a chance," said Ten Hag.
"We have the opportunity but the first focus point is always the next game and we can't win the (Europa League) trophy this week.
"We have to keep in the same mindset that every day we want to give a better version of ourselves."
The Red Devils have not won a trophy since 2017 and face Newcastle United this weekend in the Carabao Cup final.
Ten Hag has had the opportunity to dine and get some sage words from United's legendary former manager Sir Alex Ferguson earlier this week.
"I always enjoy speaking with people who have a lot of knowledge, a lot of experience. He wants to share it; he wants to help and support," Ten Hag said.
"You feel Manchester United is his club. He feels so committed and he wants that we are doing well.
"It was a great night and I look forward to the next night with him."
