SYDNEY, Jan 2 (Reuters) - Russian Daniil Medvedev"s 2022 season opened with a stunning defeat at the hands of Frenchman Ugo Humbert at the ATP Cup on Sunday, while Italy"s Matteo Berrettini suffered a straight-sets loss to Australian Alex de Minaur. World number two Medvedev had been expected to seal the Group B tie for Russia after Roman Safiullin beat Arthur Rinderknech in the opening singles, but Humbert"s 6-7(5) 7-5 7-6(2) victory kept France alive at 1-1 going into the doubles. Medvedev, however, changed his shirt and returned to the Ken Rosewall arena alongside Safiullin to clinch the tie for the defending champions with a 6-4 6-4 win over Fabrice Martin and Edouard Roger-Vasselin. "I"m feeling very bad physically, that"s all I can say," Medvedev said. That was little surprise after his titanic contest with Humbert, who was in inspired form and clung on tenaciously whenever it looked like Medvedev might get away from him. Medvedev squeezed through the first set in a tiebreak but had to go the distance after giving up a 3-0 lead to cede the second set to the 35th-ranked Frenchman. The tiring Russian looked to have run out of patience in the final tiebreaker and Humbert secured the biggest win of his career on his second match point with a rasping backhand return. "I"m not feeling very good now but I"m very happy," Humbert laughed. "It was a great match." In Group B, world number seven Berrettini was beaten on his return from injury as Italy slumped to a 2-1 loss to Australia, who were without James Duckworth after he was forced to pull out with a hip problem. Berrettini, who withdrew from the ATP Finals and Davis Cup due to an abdominal injury, struggled for rhythm as De Minaur prevailed 6-3 7-6(4) despite nearly blowing a 5-3 lead in the second set. Jannik Sinner had earlier put the Italians 1-0 up with a routine 6-1 6-3 win over Max Purcell. Berrettini returned for the doubles decider alongside Simone Bolelli but the duo were no match for John Peers and Luke Saville, who clinched the tie with a 6-3 7-5 win. Dan Evans proved to be the unlikely hero for Britain in Group C when he won two matches, including the crucial doubles rubber with Jamie Murray, to guide them to a 2-1 victory over Germany. Evans powered past Jan-Lennard Struff 6-1 6-2 to give Britain the lead before world number three Alexander Zverev restored parity with a 7-6(2) 6-1 win over the up-and-coming Cameron Norrie. "The first match of the year is never going to be the best match of you"re life. But I"m pretty happy as I did my job. We"re here to try and win," said Zverev. But Evans played spoiler as he and Murray swept to a comfortable 6-3 6-4 victory over Zverev and Kevin Krawietz to take the tie at Sydney"s Olympic Park. Earlier, Canadian Denis Shapovalov was a late withdrawal from his singles match against American John Isner at the $10-million men"s team tournament. The world number 14 had been forced to isolate in his hotel room after a positive COVID-19 test upon arrival in Sydney. "I just didn"t feel ready physically yet, so we did what is best for the team," said Shapovalov, who later took to the court to play doubles with Felix Auger-Aliassime. That was a dead rubber, however, as Isner had beaten Shapovalov"s singles replacement Brayden Schnur before Taylor Fritz downed Auger-Aliassime to give the U.S. a 2-0 lead in the Group C clash. Isner and Fritz also won the doubles rubber to put a 3-0 gloss on their nation"s first ATP Cup tie victory.