Davydenko swept by Rainer Eitzinger 6-1, 6-1 to start off his quest for a third Hypo Group title in four years. He won the event in 2005 and 2006.
Rain has been a problem for schedulers, who saw all matches Sunday washed out and lost three more to the elements Monday.
Sixth-seeded Andreas Seppi won his match but needed to rally from a poor first set for a 1-6, 6-4, 6-3 win over Ernests Gulbis.
Local favorite Jurgen Melzer collected a first-round win with a 7-5, 6-2 victory over Donald Young and Daniel Gimeno-Traver topped Werner Eschauer 6-4, 6-2. Also Monday, Ivan Navarro took out Vincent Spadea 6-4, 6-4 and Jiri Vanek outlasted Martin Verkerk 7-5, 4-6, 6-2.