Tracy Austin

NEW YORK - Maria Sharapova, seeded second at the U.S. Open, is headed home earlier than just about anyone would have expected.

The Russian’s surprising, error-filled loss to scrappy Polish teenager Agnieszka Radwanska Saturday in the third round at the U.S. Open was obviously painful.

It has been a difficult season on the court for Sharapova, who has not been in top form since winning the U.S. Open last year. She’s only won one title this year — on the hardcourts in San Diego in late July — and has struggled at the majors. Sharapova has not had the kind of year almost all expected of her.

Overall, a disappointing 2007
At the Australian Open in January, Sharapova literally got wiped out in a straight-sets loss to Serena Williams, who had not played in months, and was not considered a threat to win Down Under.

Sharapova did advance further than anyone anticipated at the French Open at Roland Garros. She says she does not like playing on clay, claiming that she feels like a "cow on ice" on the slippery surface. But in her semifinal, Sharapova simply fell flat in a straight-sets loss to Serbian teen Ana Ivanovic, one of the rising stars on the WTA Tour.

And then in the fourth round at Wimbledon, it was Venus Williams who stepped on Sharapova in a straight-sets victory. Not to discredit Venus, who averaged 115 mph on her first serves, but remember that Sharapova, the 2004 champion at Wimbledon, had a 3-2 lead in the second set before Venus closed out the match by winning the last four games.

What went wrong
Sharapova lost all of two games in her first two matches at this hard court major, but she crumbled at crunch time again on Saturday. She won eight straight games and led 2-0 in the deciding set, only to lose the last six games. That is surprising, especially when you consider that Sharapova has won two majors and was playing an 18 year-old with one tournament title to her credit.

Still, Sharapova committed a whopping 49 unforced errors and became the first second-seeded woman since 1981 to lose before the quarterfinals at the U.S. Open.

But take nothing away from Radwanska who played with both smarts and moxie, and seemingly without fear of this star player. That said, I’ll bet Radwanska — who won junior titles at the French Open in 2005 and Wimbledon in 2006 — got a confidence boost in her victory in Miami against Martina Hingis in March.

Sharapova’s serve was also a huge problem against Radwanska. Sharapova is slicing the ball a bit too much. Perhaps she felt the effects of a lingering shoulder injury. Many have said that New York’s swirling winds were a bother too. Regardless, Sharapova had 12 double faults and won only 23 percent of her second-serve points.

That’s unacceptable.

Jim Rogash / Getty Images The Week in Sports Pictures The nation grieved for those hurt, killed and affected by the Boston Marathon bombings. After one of the suspects was caught on Friday — following a day-long lockdown and manhunt — sports returned to Boston over the weekend.

A questionable tactic
Throughout the match, Radwanska consistently crept closer to the service box, daring Sharapova to try for aces. The teenager did it claiming that Sharapova "hates it" when opposing players move while she is serving. Sharapova got testy after the match when asked about the subject, claiming that she does not think about where opponents are standing while she is serving.

Clearly, it was a ploy that worked, and it got into Sharapova’s head a little bit. But I’m not really expecting other players to use the tactic against Sharapova since it is a strategy normally used at the junior level.

Don't miss this on MSNBC.com Pass it on: Sons of infertile men may be next The eight biggest Olympic marketing debacles Reality show judges range from wise to wacko Cosmic Log: Is this your jetpack? Forget your inhibitions: World's sexiest islands

There is an unwritten rule of sorts that once you get on the pro tour, you simply do not stand well inside the baseline while an opponent is serving.

But it is worth noting that Michael Chang used that strategy effectively in a legendary five-set victory over Ivan Lendl when Chang, at age 17, went on to become the youngest player ever to win Roland Garros.