Andy Murray received a standing ovation after marking his first match as world number one with a 6-3 6-2 victory over Marin Cilic at the ATP World Tour Finals.
The O2 Arena in London was certainly a fitting stage for Murray officially to step out on top of the world for the first time and he kept his winning run going with a comfortable win.
That made it 20 successive wins for the Scot, who needs to match Novak Djokovic's performance this week to ensure he holds onto the ranking until the end of the year.
Djokovic won his opening match against Dominic Thiem on Sunday and Murray knew he could not afford any slip-ups.
The 29-year-old said: "It was a great atmosphere in here. I played one of my best matches that I've played here and I'll just try to keep it going until the end of the year."
.@andy_murray defeats #Cilic for the loss of just five games to move equal top of Group John McEnroe pic.twitter.com/ujSYtseKuv
— TennisTV (@TennisTV) November 14, 2016
A tally of two winners and 14 unforced errors in the opening set was hardly world-leading stuff but it was good enough for Cilic, whose garish shorts were more memorable than his shots.
By the end, Murray was playing some fine tennis - and victory over Kei Nishikori on Wednesday would very likely be enough for a first semi-final appearance here since 2012.
The international nature of the crowd at the O2 means it has not always felt like a home event for Murray - but there was no doubting who the favourite was this time.
The arena was on its feet when Murray was announced as the world number one.
The 29-year-old was taking on the lowest-ranked player in his group but victory was not a formality, particularly considering Murray's surprisingly poor record here.
Cilic arguably came into the tournament as the most in-form player in the world behind Murray, having won a title in Basle last month and then claimed a first win in 15 against Djokovic at the Paris Masters.
The Croatian, who is working with Murray's former assistant coach Jonas Bjorkman, also won his most recent meeting with the Scot in Cincinnati in August.
Neither man hit any great heights in the opening set but it was Murray who took his chances.
After saving break points in the opening game, he had the better of three successive breaks and then held for 4-1 despite serving two double faults.
Nerves would have been understandable but there were enough errors from his opponent for him to hold onto his advantage and take the opening set.
Cilic possesses both power and very good movement for a man of 6ft 6in, but Murray is the master of making life awkward for tall opponents.
He was beginning to play more like the man who has won his last four tournaments and a forehand winner earned him the first break of the second set and a 3-2 lead.
Cilic simply had no answer now and Murray wrapped up victory in an hour and a half when Cilic netted a forehand.
Stan Wawrinka's hopes of reaching a fourth consecutive semi-final at the ATP World Tour Finals were dented by an opening loss to Kei Nishikori.
The third seed had never previously lost to anyone at the tournament other than Roger Federer, Rafael Nadal or Novak Djokovic.
But he was well below his best and fifth seed Nishikori ran out a convincing 6-2 6-3 winner.
The victory boosts Nishikori's hopes of overtaking Wawrinka to finish the year as world number three, and he said: "That's my goal for this week, try to win matches and try to reach number four or number three.
"I've been playing really well this year so I'll try to keep it up. Today I think I was very solid from the first game and I was very confident. I thought I played a good match."
Watch this @keinishikori exquisite full-stretch, no-look, over the shoulder backhand volley! https://t.co/kRsZ9udpkC https://t.co/KYzAfMmtVg
— TennisTV (@TennisTV) November 14, 2016
Wawrinka led their head-to-head 4-2, winning their most recent meeting in the semi-finals of the US Open before going on to win his third grand slam title.
But, brilliant as he can be, the Swiss is also erratic and there were far too many errors in the opening set in particular.
Nishikori's movement was sharper and his ball-striking cleaner, and he earned his rewards with five games in a row to win the first set.
Wawrinka's struggles were rather summed up by two double faults to hand Nishikori a second break of serve, and the Japanese star clinched the set with a fine backhand volley.
His net play was a feature of the set, the fifth seed winning seven points with volleys.
Wawrinka tried to fire himself up at the start of the second set and initially played better, but he then misjudged a return that landed on the baseline and was broken in the fifth game.
The 31-year-old never looked like recovering and, when he drilled a backhand long after an hour and seven minutes, the match was over.
