Will Madonna receive a very special gift to mark her milestone 50th birthday on Aug. 16th? So claims the London Sun, which believes the Big M and husband Guy Ritchie are "on the very cusp" of adopting another child from Malawi.

According to the tabloid, the tot in question is a 3-year-old named Mercy, whom the lately razor-sharp-cheekboned pop icon was first rumored to be adopting this time last year (there were reports the toddler's uncle put the kibosh on the plan).

"Madonna's representatives have been visiting the girl," Malawian adoption official Penstone Kilembe is quoted as saying. "The adoption is now advanced -- all the government is waiting for is Madonna to forward the petition of adoption formalities."

Madonna introduces son David to baseball as they brave the rain at Yankee Stadium on June 22.

Adds Kilembe, who was involved in the controversial and drawn-out -- but ultimately successful -- adoption of Madonna and Guy's button-cute son David, 2, "Then Mercy will be able to leave the country for a new life."

The supposed restarting of the adoption process, which was allegedly put on hold four months ago, has led insiders to posit that Madonna and Guy's Alex Rodriguez-rumor-rocked union is "back on track."

(By the way, the New York Yankees star is reportedly planning to donate $500,000-plus to the red string-devoted star's Raising Malawi charity, which is aimed at helping children in the poverty-stricken African nation.)

"The adoption process in Malawi is so long and stressful that all the legal wrangling put a huge strain on their marriage," a confidant maintains to the paper. "They dropped proceedings to pour all their energies into each other. But Madonna now feels they are stable enough to press ahead with the adoption again."

And while the insider says Madonna "fell in love" with Mercy when she met her at an orphanage last year, there are purportedly some objections to the tyke possibly being relocated to the Ritchies' palatial London residence.

The Sun quotes one Lucy Chekechiwa, 60, identified as Mercy's grandmother, as voicing opposition to her being adopted by a non-Malawian family.

"We know that it is Mercy who Madonna really wants. We heard it is because my granddaughter is such a beautiful, happy child," she says. "Twice I have told the adoption people that I do not want Mercy to go outside the country. But they keep on at us. Now they say that Mercy will be leaving us, but can return at age 18. Yet I might not be alive then."

But Mercy's grandma can apparently rest easy, because Madonna's spokeswoman tells us the adoption report is so much fiction.

"This is not at all true," Liz Rosenberg insists to MSN Entertainment. "Madonna is getting ready to go on a worldwide tour and there are absolutely no plans for them to adopt."

Adds the rep, "This is an old rumor that someone has reactivated. I have no idea why, since it's completely false."

In other Madonna news, it turns out that just because she has biceps that can crush walnuts, it doesn't mean she's invincible.

The exercise enthusiast, who is gearing up for the launch of her Sticky & Sweet tour on Aug. 23, was seen with a bandage around her left ankle while out in New York over the weekend.

According to the London Mirror, she's suffering from a sprain, an injury that could delay her birthday soiree for a couple of weeks.

Seems Madonna was looking to invite about 50 guests to a "lavish" shindig at her English estate, including friends such as Gwyneth Paltrow and Stella McCartney, along with some "Kabbalah associates" and a few "officials from Malawi" who assisted with her adoption of David.

"Plans are very hush-hush, but Madonna is definitely going to celebrate her milestone in style," a source tells the paper. "Unfortunately not everything has gone as expected as she's had many other things on her mind -- not least rehearsals for her Sticky & Sweet tour. On top of all the stress of this, she twisted her ankle over the weekend."

Continues the chatty snitch, "She views this as a sign that perhaps she should postpone the formal birthday bash and play it by ear instead. Madonna now reckons it'll go ahead during a three-day break in the tour towards the end of the month, not next weekend."

While Madonna's rep denies she's hurt her ankle or canceled a party, the paper says she still plans to celebrate her big day with an intimate "family get-together," which we assume will include Guy, David, daughter Lourdes, 11, and son Rocco, 7, but not unauthorized bio-writing brother Christopher Ciccone.

He tells Heat magazine that his powerhouse sister has maintained a cone of silence since the release of his tome, "Life With My Sister Madonna," but he says he already has a thrifty present all picked out for her half-century mark.

"This book is her birthday present from me," he zings. "And she can't take it back if it doesn't fit. Happy birthday, honey."