Having pulled out of her season-opening event in Auckland after suffering a back spasm, Raducanu had not played since mid-November before her first-round win over Ekaterina Alexandrova.

Raducanu struggled with her second serve against the Russian 26nd seed, hitting 15 double faults which she put down to a remodelled serve and early tournament nerves.

Another on her first service point against Anisimova was not an encouraging start.

Although she quickly stemmed the flow, Raducanu's serve was regularly punished by the American's explosive hitting.

But Anisimova - who reached the French Open semi-finals as a 17-year-old in 2019 and is re-establishing herself after taking a mental health break from the sport in 2023 - also had issues with her serve and handed over the opening set with a double fault.

At the start of the second set, there were further signs of Raducanu's back issue having an effect.

Afterwards, Raducanu said she had not "fully investigated" whether it was related to the back spasm.

"When you haven't played a match in so long, then to have two really physical ones, I think small niggles are going to come up here and there," she added.

"I'm just hoping that it is that."

After stretching out the area between points, three double faults handed over another break and Raducanu called the trainer when she lost serve again for 3-0.

The physiological, and perhaps psychological, boost helped her immediately.