United were beaten 2-1 by Ancelotti's Chelsea last Saturday as the Blues went two points clear at the top of the table.
But worse was to follow for Sir Alex Ferguson's side as they were dumped out of the Champions League on away goals by Bayern Munich on Wednesday night.
The double setback has convinced Ancelotti that United will now have even greater impetus to try to retain their status as domestic champions.
"It is not good news they are out of the Champions League because they will be focused on the Premier League and we have to pay attention because they are close to us," Ancelotti said.
"They have the experience to stay focused on the Premier League because they have experience and quality.
"I would have preferred for Manchester United to have beaten Bayern Munich and stayed in the Champions League because it would be easier for us.
"United had a bad week, they lost the quarter-final and they lost against us. Now they have the possibility to come back against us and play well and win."
to play too. After three months of being injured he will need games."