Career
He can play both guard positions as well as the small forward position. Club season
Before starting his professional career, Grigonis played in the NKL with the Žalgiris-Arvydas Sabonis school for four seasons. He was an important contributor to the team during his debut season, and established himself as a leader by his third season.
On 15 May 2013, Grigonis was brought into the main Žalgiris roster for a game against British Columbia Nizhny Novgorod in the VTB United League.
According to the new Žalgiris director P. Motiejūnas, Grigonis will see more playing time next season. Foreign the 2013-2014 season, Grigonis was loaned to the Spanish second division team Peñas Huesca.
Finished the regular season, he was elected in the All-LEB Oro team National team
Grigonis represented Lithuania in the U–16, U–18, U–19 and U–20 youth tournaments.
He led his team to two silver medals and a bronze medal while participating in four tournaments.
During the 2012 International Basketball Federation Europe Under-18 Championship semifinal game, he scored the winning shot against Serbia. As a result of his contributions to the team"s success, he was chosen to be included in the All–Tournament Team. In 2014, coach Jonas Kazlauskas included Grigonis in the preliminary 24–player candidate list for the senior national basketball team