"He is holding up with strength and dignity," the Oscar and Tony winner, 41, said Wednesday at the golfing world's Ryder Cup "Welcome to Wales" gala in her native country's capital, Cardiff. "He is about to finish his treatment and the doctors could not be happier."
Receiving some support from Prince Charles, the celebration's guest of honor, Zeta-Jones was told by the prince, "Give him my best. Healing thoughts," reports the Western Mail.
As a friend of Zeta-Jones's told PEOPLE: "Catherine said Michael was home rooting for the American team, while she is rooting for team Europe. It keeps thing interesting!"
As for the event, which attracts such world-class golfers as Tiger Woods, the friend said of Zeta-Jones's attendance, "This has been on her calendar for months, and Michael insisted she go. They are both golf lovers. This is important to Catherine and to Wales, so she made it a quick trip to be a part of the important night, and get right home."
As the actress told the crowd in Wales, "Michael will be on Skype screaming for the Americans. He wishes he could be here."