Arsenal were ravaged by food poisoning in Shanghai that ruled several key players out of their preseason friendly with Bayern Munich on Wednesday, manager Arsene Wenger said.

The Frenchman revealed the sickness that had swept the Arsenal camp, coupled with the severe heat in China and long flights, made for far-from-ideal preparations for another taxing campaign.

Wenger was shorn of Olivier Giroud because of food poisoning, then captain Per Mertesacker pulled out of the game just moments before kick-off because he too fell ill with the same problem.

New signing Sead Kolasinac also had to come off before the break, while Aaron Ramsey and Theo Walcott were only substitutes because they were sick.

Wenger’s ailing men were outplayed for long periods by Bayern before salvaging a last-gasp 1-1 draw and then winning 3-2 on penalties.

Arsenal were particularly poor in the first half in the 36 degrees Celsius (97F) heat and Wenger admitted that the extreme conditions in Shanghai were “a shock” after flying in from Australia, which is in its winter.

“I was a bit scared that tonight we could have big problems and in fact in the first half we suffered a bit,” said Wenger, under pressure to get Arsenal back in the Champions League this season.

“Ramsey finished the game, but Walcott, Kolasinac, Mertesacker, Giroud, they all had a little food poisoning.”

Wenger said the club — who next travel to Beijing to face Chelsea on Saturday — did not know what caused the food poisoning.

Wenger added of the punishing preseason schedule that many top European clubs now undertake to far-flung destinations for commercial reasons: “If you ask me is it ideal physically to prepare? I’d say certainly not.

“Has it got other advantages? Yes because we can meet fans all over the world so that is very positive.”

Reserve goalkeeper Emiliano Martinez was the unlikely hero for Wenger and Arsenal, saving Juan Bernat’s soft spot kick after Gunners substitute Alex Iwobi nodded in the leveller right at the end of normal time.

Robert Lewandowski had needed just nine minutes to fire German champions Bayern ahead from the penalty spot as they outplayed Arsenal, before Iwobi’s late intervention meant the game went straight to penalties.

Both sides fielded a mixture of first-team regulars and reserves, with new Bayern signing James Rodriguez and new Arsenal striker Alexandre Lacazette starting.

Bayern play AC Milan in Shenzhen, southern China, in their next warm-up game. (AFP)