After spells in the youth of Manuel Belgrano, Unión de Belgrano and Almirante Brown, Grahl started his senior career with the latter in 2008.[2] He played six times between 2008 and 2010.[3] In July 2010, Grahl joined Argentine Primera División side Boca Juniors on loan.[2][4] His loan was made permanent in 2011.[4] Grahl left Boca without featuring in 2013 and returned to Almirante Brown.[4] He scored the first professional goal of his career for the club on 8 December 2013 in a Primera B Nacional draw with Huracán.[1] In the 2013–14 season, Grahl made thirty-two appearances for Almirante Brown and scored six goals.[1]
In July 2014, Grahl joined Atlético Tucumán of Primera B Nacional.[1] He scored his opening Tucumán goal in his second appearance in an away win versus Unión Santa Fe.[1] He played twenty times in his debut campaign, prior to participating in eighteen games in Tucumán's title-winning run of 2015.[1] He failed to make an appearance in the 2016 Argentine Primera División and was subsequently sent out on loan to Almagro for the 2016–17 season.[1] He played thirty-eight matches and scored three for Almagro.[1]San Martín signed Grahl in July 2018.[1] His league debut was also his 100th career appearance; vs. Belgrano on 11 August.[1]
