Just three days after losing the second leg of their Supercopa de Espana clash with rivals Atletico Madrid, Los Blancos kicked off their Primera Division campaign at the Santiago Bernabeu, with Karim Benzema and Cristiano Ronaldo netting for the hosts.
However, Madrid laboured for long periods and Ancelotti admitted afterwards that the European champions had struggled with the quick turnaround.
"We were tired," the Italian told reporters. “We only played three days ago and it's not easy to go straight back into action after that amount of rest.
"Having said that, though, I think we controlled the game. We're not at our best yet. We need to quicken the game up but I'm sure that will come with time."
Madrid's next outing in La Liga comes on Sunday, when Ancelotti's men travel to San Sebastian to take on Real Sociedad.