Tennis: Serena survives Pironkova test to reach US Open semis

September 10, 2020 2:49 AMNEW YORK (REUTERS) - Serena Williams was forced to dig deep to secure a 4-6 6-3 6-2 US Open quarter-final victory over unseeded Bulgarian Tsvetana Pironkova on Wednesday (Sept 9), keeping alive her latest bid for a record-tying 24th Grand Slam singles title.