Eitzinger started playing tennis when he was five. On the Junior Tour he played around 50 matches between 1999 and 2001 and was placed in the top 200 of the junior world rankings.
For the pros, he played on the third-class ITF Future Tour from 1999 , and in 2002 he won more than one match for the first time. 2003 was in a final of a future in Italy. In 2004 Eitzinger won two futures, achieved some other good results and celebrated its premiere on the ATP Challenger Tour . As a result, at the end of the year he was in the top 500 for the first time in the world rankings, with 315th place. After another tournament victory at Futures, he was able to compete regularly on the higher endowed Challenger Tour. There he reached after a quarter-finals in Saransk , his first semi-final in Vigo and another in Budapest . In October of that year he was in the main field of an ATP World Tour event for the first time , where he was able to make his debut match against Nicolás Almagro in Vienna positive and won in two sets. In the last sixteen he lost to David Nalbandian . In doubles he also achieved his first Challenger tournament victory in Banja Luka .
2006 was his most successful year. He was able to qualify for a Grand Slam tournament - at the Australian Open in Melbourne - for the second time since 2005 . There he failed, however, as well as later that year in qualifying at the French and US Open . In April he won the first of two Challenger titles, in the final he had the upper hand against Paolo Lorenzi in San Luis Potosí . In the middle of the year it reached position 166, its highest rating in the world rankings. Eitzinger also made his only appearance for the Austrian Davis Cup team against Mexico, where he won the no longer relevant match against Daniel Garza . After that, he lost ground in the world rankings and had to increasingly compete in futures again. Until 2009, when he won his second challenger in Qarshi in singles and his second title in Banja Luka in doubles, his ranking was mostly between 250 and 350 places, before he barely won any matches and ended his career in early 2011.