The most missed player at this summer's World Cup despatched the Gunners with a first half header for Monaco.
The 28-year-old, missing since suffering a serious knee injury in January, rose to power home a header and secure a 1-0 win.
Fifteen years to the day since Thierry Henry joined the Gunners from Juventus, Alexis Sanchez made his first start for the North London but could not change the outcome of the Emirates Cup clash.
Sanchez was replaced with 15 minutes to go, while Arsenal considered themselves unlucky not to be awarded a late penalty when Chuba Akpom was fouled.
