[1] On 4 August 2008 he was invited to a trial period at Chelsea, and after impressing during his stay he was granted a scholarship deal with the club.

On 5 February 2011, he made his professional debut, against River Plate, replacing David Texeira in the 76th minute and netting a last-minute goal of a 4–1 home routing.

[6] On 9 July 2012, Pírez joined CE Sabadell FC in a one-month loan deal, mainly to regain match fitness.

[13] On 19 December 2017, it was announced that Pírez would join United Soccer League side Tulsa Roughnecks ahead of their 2018 season.

[14] Pírez was capped by Uruguay national under-20 football team for the preliminary squad for the 2011 South American Youth Championship.