The globe-trotting pair appeared to have taken their budding relationship to the next level this month with a quiet vacation together on the Caribbean island of Antiqua, the website said.
The report cites sources close to both Woods and Vonn who said the two superstars stay in close contact while on the road and met through "the ski community," The Sporting News said Saturday.
"Tiger is an active skier," a Vonn source said. "Lindsey has been teaching Tiger's kids, Sam and Charlie, how to ski."
Vonn, 28, is recently divorced and told The Denver Post recently she and the 37-year-old Woods were "just friends," Sporting News said.
Both stars have declined to either confirm or deny the reports.