PARIS — When Maria Sharapova received the results of an MRI last month, she learned the pain in her shoulder was very close to a serious, and perhaps season-ending, injury. Sharapova yesterday described it as severe tendonitis, nearly a tear. She caught it early enough to avoid surgery, but doctors said it would sideline her for four to six weeks, unless she took a shot of cortisone to ease the inflammation.

Sharapova isn’t fond of needles — that alone might have qualified as a reasonable excuse to skip this year’s French Open in favor of rest and grass-court preparation for Wimbledon, her favorite tournament. In four tries at Roland Garros, she’s lost in the first round, lost in the fourth round, and made the quarterfinals twice. Last year she suffered a monumental fourthround defeat to countrywoman Dinara Safina: Sharapova led 5–1 in the third set and then proceeded to lose 18 of 21 points and the last six games of the match.

Suffice to say, Sharapova hates clay. Yet she hates layoffs even more. She said there was no missing this year’s tournament, even though she was limited to three preparation matches in Istanbul, where she struggled to defeat two low-ranked players and lost to Aravane Rezai, a talented but inconsistent 20-year-old Frenchwoman who lost in the first round at Roland Garros this year. She also had to endure that long, painful needle, which left her sore and unable to pick up a racket for two weeks.

“The French is probably going to be the most challenging event that I’m going to play in my career,” she said. “And I play tennis because I love challenges.”

This entire season has been a challenge for Sharapova, perhaps unexpectedly after the way she finished 2006. At the U.S. Open, she overwhelmed Justine Henin with hard and well-placed serves and her powerful forehand. She looked about ready to assert herself as the player to beat on the women’s tour, especially at major tournaments.

Signs of shoulder trouble were apparent at the Australian Open. Sharapova barely escaped the first round and played just well enough to reach the final. Her serve never clicked, and her loss to Serena Williams, 6–1, 6–2, was an embarrassment. Since then, she’s played four tournaments and hasn’t won any of them (in one, she retired in the semifinals).

Sharapova didn’t play particularly well in her first-round match yesterday against France’s Emilie Loit, a lefty who’s not afraid to volley or hit drop shots. Her shoulder still hurts at times, and her serve suffers for it: She was broken three times and hit her first serve around 90 mph the entire match before prevailing 6–3, 7–6(4). Time and again Loit ran Sharapova side to side, often making the 20-year-old Russian flail her legs like a colt trapped on ice.

Despite having started tennis at age 4 and training at Nick Bollettieri’s tennis academy in Florida since age 9, Sharapova does not, as many might expect, possess excellent technique. It’s her competitive spirit that’s brought her two major titles and, for a few brief moments, the world no. 1 ranking. Even injured, she’ll have her chances here, especially considering the draw she’s received (both Williams sisters are in the other half, and Svetlana Kuznetsova, the no. 3 seed who looked to be in fine form yesterday during her 6–0, 6–3 first-round defeat of Ekaterina Bychkova, wouldn’t stand in her way until the semifinals).

“I’m willing to fight as much as I can,” she said. “And even without a serve, I’m good enough to win many matches.”

Sharapova is not the only woman struggling at this rainy, cold French Open, or for that matter, during this humdrum women’s season. Venus Williams, who had the look of a French Open title contender last year before she bowed out to Nicole Vaidisova in the quarterfinals, hasn’t been on her game since winning her first tournament of the season. Yesterday was no exception, as she nearly blew a 5–1 lead in the second set against fellow American Ashley Harkleroad. Williams won 6–1, 7–6(8), despite numerous loose forehands and consecutive double faults in the tiebreaker. Five times Harkleroad failed to convert a set point.

Williams said she lost concentration after realizing that she had set a tour record for fastest serve: 128 mph. She can’t afford such lapses against her next opponent, Jelena Jankovic, the fast and feisty Serb who has risen to no. 4 in the world rankings and has won three titles this year, including on clay in Rome. She met Williams on Har-Tru clay in Charleston, N.C., and Jankovic won in three sets. She promised to be ready.

“I have to improve on some things, but I feel quite confident,” Jankovic said.

Justine Henin, the two-time defending champion, looked rusty yesterday, too. She took a 5–0 lead against 16-year-old Austrian Tamira Paszek and then needed all the energy she could muster to win the first set 7–5. She took control after a rain delay, winning the second set 6–1. She’ll play Italian Mara Santangelo on Friday, Henin’s 25th birthday. Weather permitting, of course.

tperrotta@nysun.com