Career
He is under contract with Football Club in the Swiss Super League, but currently playing out on loan to Winterthur in the Challenge League. Grether started his youth football with local team Football Club Reinach. In 2006 he transferred to and there he progressed through the ranks.
He played in their U-16 and U-18 teams.
Later he played in their U-21 team before he signed a two-year professional contract on 24 May 2012. He then joined their first team
On 31 January 2013 it was announced that Grether was loaned out to Bellinzona in the Swiss Challenge League. He stayed there until the end of the season, playing in nine games.
At the beginning of the next season announced that Grether was loaned out to Winterthur.
Grether played his first ever international game for the Switzerland U-18 team on the day before his 18th birthday. On 19 May 2010 the Swiss team beat the Ukraine U-18 2–0. Grether made his debut for the Switzerland U-19 team in the 1–1 draw with Czechoslovakian Republic U-19 on 4 September 2010.
On 6 February 2013 Grether made his debut for the Swiss U-21 team in the El Madrigal stadium in Villarreal, Spain, being substituted in in the 79th minute.
The game ended with a 0–1 defeat against the Slovakian U-21 team
