[6] Lekue made his official debut with the first team on 15 August 2015, coming on as a second-half substitute for fellow youth graduate Sabin Merino in a 4–0 home rout of FC Barcelona in the Supercopa de España.

[12] On 24 November 2016, Lekue netted his first European goal to win a UEFA Europa League group match 3–2 at home to US Sassuolo Calcio.

[16] Lekue played rarely under Gaizka Garitano, and looked for a new club in the January 2021 transfer window, but was reinstated by new manager Marcelino and won another Super Cup that month, again against Barcelona.

[17] That April, he was involved in two Copa del Rey finals in one month, losing both to Real Sociedad and Barcelona respectively; he played the latter 4–0 defeat as a half-time substitute.

[19] On 22 May 2016, Lekue was called up to the Spain national team by manager Vicente del Bosque, after Jonny withdrew due to "personal reasons".