Ranar 24 ga Satumba, 2020, Martínez (a wancan lokacin da aka danganta shi sosai a cikin kafofin watsa labarai tare da komawa Athletic Bilbao) ya zira kwallaye a cikin karin lokaci don lashe 2020 UEFA Super Cup
don Bayern Munich tare da nasara 2-1 a kan Sevilla; shi ne burinsa na biyu a wasanni biyu a gasar cin kofin UEFA. Bayan da ya zira kwallaye mai mahimmanci a karin lokaci don Bayern kamar yadda ya yi a baya a 2013 a kan Chelsea a wasan karshe na UEFA Super Cup, ya shahara sosai ya sami laƙabin "Mr. Super Cup" (daga baya ya zama sananne a cikin kafofin watsa labarai na wasanni) daga abokin aikinsa Thomas Müller wanda ya zama ɗan wasan wasan. A ranar 4 ga Mayu 2021, Bayern ta sanar da cewa Martínez zai bar Bayern a ƙarshen kakar wasa, tunda ɓangarorin biyu sun yarda ba za su tsawaita kwantiraginsa ba.