It was not outlandish to predict that one of the Williams sisters would lose in the first round of the Australian Open. That loser, though, seemed almost certain to be Serena.

Instead, Serena barely survived and Venus did not, coughing up 65 unforced errors to the unknown Tszvetana Pironkova, an 18-year-old from Bulgaria playing her first Grand Slam tournament.Venus could not manage a game in the second set, losing 2-6, 6-0, 9-7.

Serena, who played just as poorly, luckily ran into an opponent who played worse than she did: Na Li, ranked no. 52.The 23-year-old native of China made 58 errors to Serena’s 45.

For Venus, it was another of her confounding up and down performances. She made just 10 errors in the first set, hit most of her approaches deep, and smothered Pironkova at the net, winning 9 of 12 points. Errors did not hurt her in the second set, but carelessness did. Her approaches were too short (she won just 4 of 10 at net) and she won only five of 17 points on her serve. Only in the third set did she miss her groundstrokes with abandon, 41 errors in all.

Afterward, Venus talked as if it had just been one of those days. It wasn’t. She played well in the first set; anyone as quick and powerful as Venus should approach and volley often (her approaches were plenty good enough in the third set as well, when she won 18 of 22 points at net). The fact that her game disappeared after about 40 minutes was not due to a bad day, but rather a lack of conditioning and preparation.

It was sad to see how meek Venus’s serve has become (she had one ace, four double faults, and won 29% of points on her second serve). And while Pironkova deserves credit for going for her shots and not giving up, it’s not as if she is destined for stardom. She hits her forehand awkwardly and her service toss and jumping swing are inconsistent. She could win one more match this tournament, two at most.

Younger sister Serena, the defending champion here, certainly gave a good effort, though she did nothing to allay concerns about her conditioning. She was visibly exhausted, and would have suffered more had Li not made so many mistakes. Three years ago, a woman playing as poorly as Li did would not have won more than a game or two from Serena. That such a performance now pushes the former champion to three sets is astounding.

Can Serena pull it together? Last year she arrived in Melbourne in bad shape and went on to win the title. It’s worth recalling, however, that she lost a total of four games in her first two matches and did not look as heavy or slow as she does this year. Her firstround opponent in 2005 was Camille Pin of France; the two will meet again in the second round this year. Serena won 6-1, 6-1 last time, and the 24-year old Pin has remained at about the same place in the rankings (no. 130).

Great draw for Serena, and perhaps a measuring stick for the rest of us. If Serena prevails this time, she will likely face Daniela Hantuchova, no. 17. Maria Sharapova, no. 4, would follow, and the Russian would be an almost certain pick to avenge her semifinal defeat of last year.