But the momentum turned in Stephens’ favor in the second set when American Raducanu broke three times to equalize Tuesday’s game.
Raducanu struggled through some lengthy rallies in the final set, taking a 5-0 lead and finishing the game just before midnight (8am ET) in Melbourne.
“Both Sloane and I really gave everything and gave everything we had,” Britain’s Raducanu said during her court interview.
“I thought it was a high quality race with some really long rallies. I’m very happy to have come through against such a great champion like her.”
In December, she tested positive for Covid-19 ahead of an exhibition event in Abu Dhabi and returned to action in Sydney earlier this month.
Her next match at the Australian Open is against Montenegro’s Danka Kovinic, with two-time Grand Slam champion Simona Halep as a potential third-round opponent.
Another British player, Andy Murray, also got off to a winning start on Tuesday when he defeated Georgian Nikoloz Basilashvili 6-1 3-6 6-4 6-7 6-4.
Murray played in his first Australian Open since 2019, beating Basilashvili for the second time in a week, after also triumphing in Sydney in the lead-up to the Australian Open.
This time, the three-time grand slam champion showed the same courage and determination that characterized Murray’s playing career.
“It’s been three or four tough years. I’ve put in a lot of work to get back here,” said Murray, who considered retiring after the Australian Open three years ago before undergoing career-saving hip surgery.
“This is the one where I thought I might have played my last match, but it’s great to win another five-set fight like that. I couldn’t ask for more.”
There was also a straight-sets win for home favorite Nick Kyrgios against Briton Liam Broady to set up a second round against Medvedev.