Novak Djokovic made a successful return from a shoulder injury with victory over Alexei Popyrin in the opening round of the Japan Open.
The world number one had not played a singles match since retiring during his fourth-round contest against Stan Wawrinka at the US Open a month ago.
It was rumoured the problem may be serious enough for him to miss the Asian swing of events or even need surgery but Djokovic gave an upbeat assessment after his 6-4 6-2 victory over Australian Popyrin.
He said on atptour.com: "(The) shoulder is good. I have not felt anything in the previous days, including today, in the match. So I am very pleased to say that and to feel healthy."
It was a great day for Japanese players, led by wild card Taro Daniel's 6-4 4-6 7-6 (5) upset of second seed Borna Coric.
Qualifier Yasutaka Uchiyama also claimed a notable scalp, beating fourth seed Benoit Paire 6-2 6-2.
Reilly Opelka won the battle of the young Americans 6-3 6-4 against seventh seed Taylor Fritz while Denis Shapovalov was a 6-4 6-4 winner over Miomir Kecmanovic.
At the China Open in Beijing, Andy Murray produced the best win of his comeback so far, defeating eighth seed and US Open semi-finalist Matteo Berrettini 7-6 (2) 7-6 (7).
He will take on fellow British player Cameron Norrie in the second round on Wednesday.
Top seed Dominic Thiem eased to a 6-4 6-1 victory over Richard Gasquet while third seed Stefanos Tsitsipas had a tougher time against Dusan Lajovic but recovered from a set down to win 4-6 6-3 6-4.
Fifth seed Roberto Bautista Agut retired down a set and 4-1 to Sam Querrey and seventh seed Gael Monfils was ousted by John Isner but sixth seed Fabio Fognini squeezed past Mikhail Kukushkin on a deciding tie-break.
Defending champion Nikoloz Basilashvili is also through after a 6-4 7-6 (3) victory over Guido Pella while Felix Auger-Aliassime snapped a four-match losing streak by defeating Albert Ramos-Vinolas.