Lampard scored twice in the west Londoners' 3-0 win over the Brummie Blues, who had not lost for 15 games.
"We use all the pitch to attack and so Frank is able to run into the box to score,’’ said Ancelotti, according to The Daily Telegraph.
"I think he’s the best running midfielder in the world. He has this fantastic quality to time his run into the box."
Chelsea travel to Burnley at the weekend back on top of the table and Ancelotti is pleased to be putting pressure back on his side's title rivals.
"It’s good we are back at the top. We have one more point with a game in hand on United and two points more than Arsenal," he added.
"That’s important because, on Sunday United play Arsenal. Maybe we can improve our position on Saturday.’’