Serena Williams and Harmony Tan played out an epic lasting three hours and 10 minutes - and it was the 23-time Grand Slam champion who went out in a final set tie break.
Rafa Nadal was also made to work hard - but he got through.
Nine British players are into the second round - equalling the record from 1997.
Andy Murray will bring proceedings to a close on Centre Court tonight - after Novak Djokovic and Emma Raducanu return.