The leading duo shared a goalless draw last weekend, allowing Real to close the gap at the summit to three points ahead of Saturday's trip to Real Betis.
Los Blancos' only defeats so far this season have come against their title rivals, with a loss to Barca on October 26 the last time they were beaten, and Ancelotti wants his team to maintain their impressive form.
"The most difficult part is coming up and every match will be very important," Ancelotti told a press conference.
"We don't always play fantastic football. We have a lot of matches coming up and to play well in every one of them is not easy, but the team is focused, working hard and keen to do well."
Real striker Cristiano Ronaldo was awarded the Ballon d'Or on Monday night, beating four-time winner Lionel Messi into second place.
Atletico coach Diego Simeone has maintained all season that he feels his team will find it difficult down the stretch as the squad depth of Real and Barca come into play.
His team begin the second half of their season with the visit of Sevilla and they are still competing in the Champions League and Copa del Rey.
Sunday's clash will be their fifth game in 15 days in 2014 and the Argentinian has praised his backroom and medical staff for helping to keep a remarkable season alive.
"I think the club has done a great job keeping the same players," he told a press conference following the Copa del Rey victory over Valencia.
"The burden of matches begins to appear but you play, rest and eat well. You have to learn to run, play as a team to run less."
Barca face a trip to Levante on Sunday as they look to maintain a four-game unbeaten league run since their defeat to Athletic Bilbao.
The weekend's action gets under way on Friday night with Valencia making the trip to Malaga who will hope to have received international clearance for new midfielder Pablo Perez to make his debut.
Elche host Rayo Vallecano in a battle of two struggling teams on Saturday while Granada face Osasuna and Celta Vigo make the trip to Espanyol.
On Sunday, Getafe take on Real Sociedad and Almeria are the visitors to Villarreal while Bilbao host Real Valladolid on Monday night.