Pedro was due to start the game wearing a protective mask after sustaining a facial injury in a pre-season friendly against Arsenal in Beijing.
Despite being without the likes of Mesut Ozil, Alexis Sanchez and Aaron Ramsey, Arsenal was the first to threaten, Danny Welbeck heading straight at Courtois.
Willian then channeled Victor Moses in the FA Cup final and was booked for a dive in the Arsenal box.
Just 88 seconds later, from the free-kick, new signing Sead Kolasinac nodded in for the Gunners to cap a brilliant performance since coming on for the stricken Per Mertesacker.
Chelsea had Pedro dismissed for an untidy lunge on Mohamed Elneny 82 seconds before Kolasinac converted Granit Xhaka's cross, but Wenger felt an Arsenal leveller had always been on the cards, irrespective of any numerical advantage.
Arsenal beat Chelsea in the Community Shield at Wembley Stadium on Sunday through the new ABBA penalty shootout after the format was introduced for the first time.
Arsenal's mental strength has regularly been questioned in recent years, but Wenger was happy that his side showed the character to get back into the game and then go on to win it. What was even more shocking, however, was the bad penalty that £55 million transfer striker Alvaro Morata pulled wide.
Past Community Shield matches have often lacked genuine competitiveness, but the shared summer of discontent and a fierce London rivalry should guarantee entertainment on Sunday.
On several occasions, Theo Walcott was in good situations, but it is obvious that former English national team member is far away from his glory days. And things got worse for the Blues a minute later.
Chelsea had the lead just after halftime when Granit Xhaka's attempt at a clearance went high into the air and was flicked by Gary Cahill into the path of Moses, who finished from close-range. Proof that Arsene Wenger boys deserved the victory even manifested in the goal kicks that Chelsea played, 14 to Arsenal's three.