Novak Djokovic flew out of the traps as he began his ATP Finals campaign with a crushing victory over Matteo Berrettini.
The five-time champion, jousting with Rafael Nadal to finish the year as world number one, swept aside 02 debutant Berrettini 6-2 6-1.
Djokovic needs to at least reach the final of the season-ending tournament to stand a chance of overhauling Nadal, and thus equalling Pete Sampras' record of ending the year on top of the rankings six times.
The 32-year-old Serbian certainly looks like he will take some stopping in London.
He wrapped up the first set in just half an hour, dropping only four points on his own serve while breaking Berrettini twice.
There was little Berrettini, ranked eighth, could do. The 23-year-old Italian had got 75 per cent of his first serves in, regularly approaching 140mph, yet won just half of the points.
Berrettini had never played Djokovic before, and will probably not be too keen to run into the 16-time grand slam winner again for a while.
He won the rally of the match at the start of the second set with an acrobatic get followed by an overhead – earning applause from Djokovic – but still dropped serve thanks to a double fault.
Djokovic reeled off eight games in a row before Berrettini landed a blow of his own, breaking serve to trail 4-1.
But Djokovic responded in kind and went on to wrap up a one-sided victory in only an hour and two minutes.
The reigning Wimbledon champion said: "It feels great to be back. Earlier this year I had a great stay in London, and over the years I've played well in this arena.
"It was not easy for him at his first Finals match, I knew he would be nervous at the beginning and I used my experience to perform well.
"I was fortunate to get the first break and then I started reading his serve better. I played really solid throughout the match.
"I've been enjoying the conditions here for many years. It's suitable to my game, but it's never easy playing a big server like Matteo."
Earlier Joe Salisbury, Britain's sole representative in London this week, suffered defeat in the opening doubles rubber.
The 27-year-old and American partner Rajeev Ram were beaten 6-3 6-4 by South African Raven Klaasen and Michael Venus of New Zealand.
