Goals from Karim Benzema and Jese gave Real the advantage in the tie on a rare night where Cristiano Ronaldo misfired, although the result was slightly marred as Jese left the field in the second half.
However, Ancelotti allayed any injury fears for the 20-year-old in his post-match analysis.
"It was a good match, better on the defensive side, without taking risks," the Italian told the club's official website.
"2-0 is a good result, we tried to score the third and came close. We need to go out there to play because the second leg will not be easy. It is a good result but we will not be thinking about getting a 0-0.
"The two centre-backs did well. They are in very good form. The team is stronger at the back and we are recovering more balls higher up the field. We misplaced a few passes in the first half but the second was better.
"(Jese) played well, worked hard, scored and was involved in the match. He is an important player and is in good form and we have to enjoy that. He only came off because of a cramp".
Ancelotti also explained why Angel Di Maria was not involved, despite facing no action after he made a crude gesture towards his club's fans during Monday night's 3-0 home victory over Celta Vigo.
"We didn't need Di Maria because the wingers did very well," Ancelotti said.
"(Gareth) Bale did very well and was dangerous, while Jese and Cristiano combined well."
Bale completed his first 90 minutes since returning from a calf injury, and Ancelotti was pleased with his input.
"Everyone knows that he has had problems," Ancelotti said.
"He needs to get back to his best and that is why he played the entire match. He did not participate as much in the first half but was more open and looking to create more attacks in the second.
"We are all very happy. He had a problem for 20 days and is looking to get to his best."
Ancelotti also looked ahead to Saturday's Primera Division clash between pacesetters Barcelona and Atletico Madrid.
The two sides are both five points clear of third-placed Real in the overall league standings.
"It is hard to think about what the best result for us would be," Ancelotti said of the match.
"They cannot both lose, but neither can they both win. We have to win to make up points with Barcelona or Atletico."