Antonio Conte's achievements at Chelsea are "extraordinary", according to former Blues manager Carlo Ancelotti.
Ancelotti, now in charge at Bayern Munich, guided Chelsea to the Premier League title and FA Cup in the 2009/2010 campaign.
Chelsea finished 10th last season but Conte has revived their fortunes after taking over in the summer. The 4-2 win against Stoke on New Year's Eve was their 13th consecutive victory, equalling the Premier League record for consecutive wins in a season, and the Blues sit five points clear at the top of the table with a game in hand.
"What Conte is doing at Chelsea is extraordinary," Ancelotti told Gazzetta dello Sport. "Antonio has determination, ideas, personality and experience. He's mature as a coach now and I'm truly happy for him."
Chelsea have the opportunity to equal Arsenal's Premier League record of 14 victories in a row - picked up over two seasons in 2002 - when they take on Tottenham on Wednesday, live on Sky Sports 1HD.
Ancelotti has put Conte's success down to his playing career, drawing comparisons with Real Madrid manager Zinedine Zidane.
"Zidane has won the World Club Cup after winning the Champions League, and there were people who thought he was not a coach," Ancelotti added.
"The truth is Conte and Zidane had quality on the field and they've taken that into their new jobs with them."