United Kingdom, June 6 -- Tiger Woods is "doing the best he can" in rehab while his girlfriend battles breast cancer.

The golf superstar, 50, is said to be continuing treatment at a specialist facility in Switzerland, where he is expected to remain until the end of June, but continuing to try to support Vanessa Trump following her breast cancer diagnosis, which she revealed last month.

A source told PEOPLE: "The original plan was for Tiger to do three months in rehab, which should stay on target unless something major changes.

"Tiger is doing the best he can with all of the pressure on him with healing and also the legal issues he faces in coming months. This has created a great deal of stress.

"They talk and share their lives as they...