Valentine's Day star Jessica Biel celebrated her 28th birthday with her own valentine, boyfriend Justin Timberlake, in the Alps of Switzerland. Timberlake, 29, was in the country for business as Audi ambassador for the Geneva auto show, E! reports.

The couple, who continue to fend off breakup rumors, were reportedly spotted leaving their hotel arm in arm, and even went sledding down a mountain together during their Swiss weekend. (Pictured above: Biel in green, top right, and Timberlake in black, bottom left.)

Biel made headlines in January when she scaled Tanzania's Mount Kilamanjaro with a group called Summit on the Summit -- raising awareness for the global need for access to clean water -- and Timberlake's absence on that adventure seemed conspicious to some celeb-watchers.

The pair will no doubt be fighting off more gossip as Timberlake prepares to star in an upcoming comedy, Bad Teacher, with ex-girlfriend Cameron Diaz -- who he dated for four years (they split in 2007).

None of it seems to matter to birthday girl Biel, who opened up to Vogue about her relationship with Timberlake, calling it "the most precious thing that I have in my life."