BERLIN, Germany (AFP) — Serena Williams suffered a straight sets defeat in the Berlin Open doubles on Tuesday, hours after the confirmation of her return to Wimbledon to play alongside her older sister Venus. Williams and Czech doubles partner Karolina Muchova fell to Mexico's Giuliana Olmos and Erin Routliffe, of New Zealand, 6-4, 6-4. The duo lost the opening set after Williams was broken in her second service game.