"I don't feel 100 percent ready. The doctors recommended I rest so that I can recover," Kerber said in comments released through the tournament organizers.
Begu wins in Moscow while Kerber withdraws →
"It was a very good match for me, I was there from the first point," Kerber said of her easy win over Dellacqua. "It was a great feeling to go on court up 1-0, and now I'm even happier it's 2-0."
Fed Cup: Germany leads Australia 2-0 in semifinal →