California - From his knees at the middle of the net, Roger Federer struck volley after volley right back at Jack Sock until the American star finally faltered. Federer just smiled.
He's the best in the world at age 36.
Earlier, Federer emerged from the tunnel of smoke and walked onto the court greeted by roars and thousands of camera phones held high for the first Bay Area appearance of his career.
Even if this doubles match didn't officially count on Monday night, it sure mattered to all of the children in Africa who Federer is committed to helping through his foundation.
Federer waved every which way, held his racket in the air and beamed when introduced during warmups with the announcement at the sold-out SAP Centre that he had regained the No 1 world ranking.
He entertained from the start, too, praising Microsoft billionaire Bill Gates as a perfect partner.
"He knows numbers very well. He never makes mistakes on the scores," Federer cracked. "I'll do the running and Bill does the thinking."
He joked to opponent Savannah Guthrie of NBC's "TODAY" show: "You have to start looking at the ball and stop looking at me."
Federer called off Gates with, "That's mine ... that's mine, too," before Sock lobbed a winner over Gates that Federer couldn't chase down. Federer and Gates took the match 6-3.
Federer's "The Match for Africa" exhibition sold more than 15 000 tickets to benefit his foundation that supports education for children in Africa.
"This match for Africa is something extraordinary," Sock said.
The Swiss star, who at 36 is the oldest men's player to be No 1, won the Australian Open in January for his 20th Grand Slam title.
Federer and Gates also teamed up last year in Seattle.
Sock joked beforehand, "Don't hit it to Roger ... I'm winless against him for my career."
A video promoting the match featured Federer training Gates, from weight lifting - lunges with a heavy bar over his shoulders - to studying a tennis book and both ping-pong and tennis practice to work on his reflexes and skills.
"You'll train like I do," Federer said. "You are ready."
And Gates, dressed in a bright pink polo, drew oohs and aahs as he impressed with his shot-making and hustle to keep points alive.
