Igor Stravinsky | Prince Igor | Igor Smirnov | Pedro Martínez | Igor Sikorsky | Igor | Igor Markevitch | Igor Krutoy | Igor Andreyevich Polyanski | Igor Polyanski | Igor Oistrakh | Igor Kipnis | Martinez, California | Bob Martinez | Tino Martinez | Roberto Martínez | Odaline de la Martinez | Igor Ozim | Igor Nikolayev | Igor (film) | Tomás Eloy Martínez | Susana Martinez | Igor Witkowski | Igor Ivanov | Igor Grabar | Igor Butman | Igor Bališ | Igor Andreev | Dennis Martínez | Carlos Martínez de Irujo, 1st Marquis of Casa Irujo |
On 28 November 2012, at only 17, Undabarrena made his official debut with the main squad, coming on as a substitute for Igor Martínez in the 77th minute of a 2–0 away win against Hapoel Ironi Kiryat Shmona F.C. for the campaign's UEFA Europa League.