Maria Sharapova, who celebrated her 20th birthday on April 19, seems to be growing up fast. With her teen years behind her, and a very healthy bank account, the Russian has been busy keeping her life in order during her injury layoff.

She reported on her website that she celebrated her birthday by having “15 people get together at one of my favorite restaurants in LA” – much more low key than the birthday extravaganza Motorola threw for her to celebrate her 18th birthday in New York City.

Hinting that she is spending time at her Manhattan Beach residence (she also has digs in an ultra-exclusive Florida enclave), Sharapova has been working out and rehabilitating her shoulder, and from the sound of it, leading a surprisingly normal existence.

The former world No. 1 is frequently seen on red carpets or at prestigious tournaments where she is chauffered around town and pampered at luxury hotels. During her injury-enforce break, however, she’s resembled a regular 20-year-old, running errands and surprisingly opting for a do-it-yourself attitude instead of pawning off such boring details to a personal assistant, a common practice for most celebrities.

“I went to the post office to pick up some packages that were sent back,” she confessed on her website. Next was a trip to “Boutique Tarjet” – that’s Target for you average Joes – “for toilette paper and other daily necessities.

“Then I had to go to T-Mobile to start up this new Motorola Q9 I received...”

After that it’s back to work, hitting the gym to stay in shape for when she makes her return to competition. She will begin hitting balls again this week.

If it wasn’t for her posh digs and sponsor-provided Land Rover, she could be mistaken for any other twenty-something in LA, right? Sort of, until she drops into the gym with “a new diamond ring on.” Wonder if that was a birthday present? But from whom?