INDIAN WELLS (AFP) — World No. 2 Carlos Alcaraz got off to a stuttering start in his Indian Wells Masters title defense on Friday but turned the tables to beat Matteo Arnaldi 6-7 (5/7), 6-0, 6-1.

The second-round success served as a welcome fitness test for the 20-year-old Spaniard, who rolled his ankle a fortnight ago in Rio and retired from his first-round match there.

Alcaraz gathered his forces after dropping the opening set against Arnaldi, cutting his unforced error count from 23 in the first set to a mere eight for the remainder of the contest.

The reigning Wimbledon champion lost just one more game as he came through in two and a quarter hours, concluding with 22 winners.

Alcaraz said his ankle felt better than expected.

"Honestly, it surprised me," he said. "I felt great, moving normally without thinking about it."

"It was a really good match to realize that I am better than I imagined," added Alcaraz, who next plays Canadian Felix Auger-Aliassime.

Jannik Sinner and Iga Swiatek swept into the third round with identical runaway scorelines.

But there was no joy for former number one Andy Murray, who suffered a 7-6 (7/3), 6-1 loss to fifth seed Andrey Rublev to exit the event where he lost the 2009 final to Rafael Nadal.

Australian Open champion Sinner dominated Thanasi Kokkinakis 6-3, 6-0 while women's world number one Swiatek did the same to American Danielle Collins.

Italy's Sinner, seeded third, backed up his debut Grand Slam title in Melbourne with a victory in the ATP 500 level tournament at Rotterdam last month.

He remains undefeated this season and completed a 13th consecutive match victory while improving to 4-0 over Kokkinakis.

Top seed Swiatek, the 2022 Indian Wells champion and last year's Roland Garros winner who will start her 94th week on the top WTA ranking on Monday, broke Collins four times and wrapped up victory on her second match point.