(MARK BAKER ~ Associated Press)
The 14th-seeded Sharapova was unable to defend her 2008 Australian Open championship while sidelined 10 months because of right shoulder surgery. She then failed to advance beyond the quarterfinals in the other three majors last year.
The loss to Kirilenko was her earliest exit at a Grand Slam since the 2003 French Open.
Kirilenko will join Dinara Safina in the second round, after her 6-4, 6-4 win over Magdalena Rybarikova of Slovakia in the first match completed on a rainy day at Melbourne Park. The second-seeded Safina was the runner-up to Serena Williams last year.
The Marias, both Russian and both 22, clubbed 86 winners and made 118 unforced errors between them as they traded heavy ground strokes in a match that lasted 3 hours, 21 minutes and allowed the No. 58-ranked Kirilenko to square their four career head-to-head matches.
Sharapova kept going for winners despite twice being only two points away from losing the match. She ended up with 77 unforced errors and 11 double-faults.
The former No. 1-ranked Sharapova rallied from 2-5 down in the deciding set, holding serve and then breaking Kirilenko's to stay in the match. She dropped her own serve after giving Kirilenko double match point, though, her final shot landing wide.
Safina and Kirilenko played on the two covered courts at Melbourne Park. Matches on outside courts were delayed 45 minutes by rain, a change to the heat that usually confronts players at the first Grand Slam event of the season.
Five matches were completed on outside courts until play was again suspended due to rain.
No. 30 Kateryna Bondarenko of Ukraine had a 6-2, 7-6 (6) win over Romania's Raluca Olaru, Zheng Jie rallied to beat Peng Shuai 0-6, 6-1, 6-2 in an all-China match, and Russia's Anastasia Pavlyuchenkova beat Latvia's Anastasija Sevastova 6-2, 6-4.
On the men's side, No. 24 Ivan Ljubicic had a 6-1, 6-2, 6-2 win over 16-year-old wild card entry Jason Kubler, the youngest player in the draw.
Kim Clijsters was due to play after Sharapova against Valerie Tetreault of Canada. Clijsters won the U.S. Open in September in her third tournament back from time off after getting married and having a baby.
Justine Henin, a seven-time major winner, makes her Grand Slam comeback against fellow Belgian Kirsten Flipkens at Hisense Arena, the other main show court. Henin lost to Clijsters at the Brisbane International on Jan. 9, Henin's first tournament since she quit while holding the No. 1 ranking in May 2008.
Williams has won three of the seven majors since Henin last played the Australian Open. She enters this tournament as defending champion and winner of the season-ending championship, but won't play until Tuesday in the top half of the draw.
U.S. Open winner Juan Martin del Potro, No. 5 Andy Murray and No. 7 Andy Roddick highlight the early men's action. Del Potro withdrew from an exhibition tournament at Kooyong last week because of an injured wrist, but his agent said he's expected to be fine.
Nadal, who beat Roger Federer in five sets in the final last year to win his first major on hardcourts, will start the night session at Rod Laver Arena against Australian Peter Luczak.