Britain’s US Open champion was a set and a break down against 17-year-old qualifier Linda Novoska but battled back to win in three.
Elsewhere there were straight-set wins for Rafael Nadal and Novak Djokovic, but defeats for Naomi Osaka – who later said she may snub Wimbledon over there being no ranking points available – and defending champion Barbora Krejcikova.
Here, the PA news agency looks back at day two at Roland Garros.
Picture of the day
Shot of the day
Just Nadal being Nadal.
Match of the day
Taylor Fritz, the 13th seed, was pushed all the way by Argentine qualifier Santiago Rodriguez Taverna in a five-set first-round thriller. The American was made to work for every point in a 7-6 (2), 3-6, 6-3, 4-6, 6-4 win over the World number 201, playing in his first main draw match at a grand slam.
Shock of the day
Defending champion Krejcikova led 6-1 2-0 but was sent crashing out by French teenager Diane Parry, who won 1-6 6-2 6-3.
Quote of the day
Women: Barbora Krejcikova (2), Anett Kontaveit (5), Ludmilla Samsonova (25).Men: Reilly Opelka (17).
Raducanu narrowly avoided a taste of her own medicine after coming from a set down to see off 17-year-old debutant Noskova at the French Open.
In what could have been a story straight from the Raducanu playbook at Flushing Meadows, a teenage qualifier playing her first professional grand-slam match was a set and a break up and on the verge of knocking out the reigning US Open champion.
But Raducanu rallied admirably and eventually sealed a 6-7 (4) 7-5 6-1 victory to join Cameron Norrie and Dan Evans in the next round.
However, their were straight-set defeats for Heather Watson and Harriet Dart.
Who’s up next?
A quieter day three sees second seed Daniil Medvedev face Argentine Facundo Bagnis and fourth seed Stefanos Tsitsipas take on Lorenzo Musetti.In the women’s draw seventh seed Aryna Sabalenka faces France’s Chloe Paquet.