[2] He was promoted to the reserves on 23 June 2014,[3] and made his senior debut on 31 August by coming on as a second-half substitute for Pablo Hervías in a 0–3 Segunda División B away loss against CD Tudelano.

[7] He made his debut in the category on 31 August, replacing Asier Illarramendi in a 1–2 away loss against SD Eibar, but being taken off three minutes later due to an injury.

[8] On 19 July 2019, after spending the campaign nursing his knee injury, Merquelanz joined Segunda División side CD Mirandés on loan for one year.

Merquelanz was a regular starter for the Castilian-Leonese side, scoring a career-best 15 goals and helping the club avoid relegation and reach the semi-finals of the Copa del Rey.

He terminated his contract with the Txuri-urdin on 23 July 2024,[16] and agreed to a one-year deal with SD Eibar in the second division the following day, subject to a trial period.