Grebis started his professional career in 2000 with FK Liepājas Metalurgs. Making 7 appearances and scoring one goal in his first season, he later had a short spell with FK Rīga, returning to Liepāja in 2002. This time playing there for 4 straight years, in 2006 he left for Oxford United. Grebis had his contract with Oxford United cancelled by mutual consent in March 2007, as this period of his career wasn't the best. Later on he joined FK Ventspils, but in 2008 came back to his home land team Liepājas Metalurgs. He played there for two years, until 2008, making 63 appearances and scoring 48 goals. In 2009, he was the best scorer of the Virsliga championship with 30 goals in one season. This was definitely the best period in his career, while playing in Latvia. In February 2011 he joined AEL Limassol, after being on trial with them for 2 weeks. His stayin Cyprus didn't last for long, as the club decided to release him just 4 days after joining, pointing that Grebis had been diagnosed heart problems in the medical tests. Later on it was said that there were no problems with Grebis's heart, but the club had needed to find a reason to release Grebis, as the new coach hadn't wanted to keep him in the squad. A week later he signed a contract with FK Gence, playing in the Azerbaijan Premier League. In July2011 Grebis moved to FK Simurq Zaqatala. In August 2012 he was signed by the German NOFV-Oberliga Nord club Viktoria 1889. He left the club in February 2013, having played 5 league matches, and returned to the Latvian Higher League, signing with Daugava Rīga. Grebis played 9 matches for Daugava, marking 1 goal to his name, before joining FC Jūrmala in July 2013. Prior to the 2014 season Grebis returned to his home-town Liepāja and signed a contract with the newly established club FK Liepāja, led by his former international teammate Māris Verpakovskis. He scored on his debut for the club. Grebis retired after the 2018 season.
International career
Grebis made his debut for Latvia in 2008. He has collected 13 appearances and scored 2 international goals.
