The performance itself gave more than enough talking points, with Murray raising his level again to push a player ranked 12 in the world all the way before slipping to a 7-6 (7-4) 2-6 7-6 (7-2) defeat.

Murray was furious with Fognini, who is no stranger to controversy, when he shouted as the Scot was about to put away a volley in the 11th game of the deciding set.

Murray confronted his opponent at the change of ends, telling the Italian to "shut up" as umpire Fergus Murphy tried to dissuade him from taking it any further.

Having failed to serve out the match at 5-4, Murray had another chance at 6-5 but Fognini broke back once more and then dominated the tie-break, clinching victory after three hours and nine minutes.

The handshake between the pair was brief, with Murray continuing to press his point to Murphy before leaving the court.

Roger Federer marked his return to the tour with a straight-sets victory over Albert Ramos-Vinolas.

Federer, who had a bye in the opening round, had only played in the Laver Cup since his shock loss to Grigor Dimitrov at the US Open and was content with a 6-2 7-6 (7-5) success against his Spanish opponent.

On Federer's mind was the fact he had lost the last time they met, at the same stage of the same tournament four years ago, but the Swiss fought back from 1-4 in the second-set tie-break to shut down any chance of a repeat.

"He had his chances but it was a nice comeback for me and, overall, I was very happy," said Federer on atptour.com.

US Open finalist Daniil Medvedev advanced to the third round with a 6-3 6-1 win over Britain's Cameron Norrie.

Gael Monfils' hopes of qualifying for the ATP Finals next month suffered a blow as he lost 6-2 7-6 (7-1) to Hubert Hurkacz.

In the first round, Andrey Rublev upset Croatian 12th seed Borna Coric and there were also wins for John Isner, Matteo Berrettini, David Goffin and Felix Auger-Aliassime.

Australian Associated Press