ST ALBANS, ENGLAND - JULY 28: (L-R) Per Mertesacker and Theo Walcott of Arsenal during a training session at London Colney on July 28, 2017 in St Albans, England. (Photo by Stuart MacFarlane/Arsenal FC via Getty Images)
ST ALBANS, ENGLAND - JULY 28: (L-R) Per Mertesacker and Theo Walcott of Arsenal during a training session at London Colney on July 28, 2017 in St Albans, England. (Photo by Stuart MacFarlane/Arsenal FC via Getty Images)