Venus Williams notched her first Top 50 win in nearly four years in the first round of the Rothesay Classic, holding off a late comeback attempt from Camila Giorgi to triumph 7-6(5), 4-6, 7-6(6) in 3 hours and 17 minutes.

After Giorgi's final backhand went long, Williams celebrated her remarkable victory, the joint-13th longest match of 2023 so far, with a trio of fist-pumps before grinning broadly at a crowd that had been willing her on throughout.

"It was touch and go there, and I felt the support," Williams told the Ann Jones Centre Court audience after the match.

Williams' grit, shotmaking and renowned serve were all on display as she battled to her first victory over a Top 50 opponent since defeating Barbora Strycova in the first round of Beijing 2019. It was her third win against Giorgi in as many encounters, following wins at the 2015 Australian Open and 2018 US Open. Williams is just the third player this century to win a tour-level match aged 43 or over, joining Martina Navratilova and Kimiko Date.

The result was the second-longest match that Williams has contested since records began to be kept in 2008. Only her 7-6(5), 6-7(4), 6-4 loss to Urszula Radwanska in the first round of Roland Garros 2013 (3 hours and 19 minutes) was longer. It is her longest victory in that timeframe, exceeding her 3-hour, 13-minute defeat of Jelena Ostapenko 7-5, 6-7(3), 7-5 at the 2017 WTA Finals Singapore.

Photos: All this year's three-hour matches

"I thought I played really well today, and she played incredible," said Williams afterwards. "I'm so surprised she's not No.1 in the world. There were so many moments where I thought, 'This match is over,' then she would hit a shot from out of nowhere. She pushed me to be better than what I thought I could be, and it's great for me. I haven't played a lot of matches, and it's great to come through."

Williams, 43, was sidelined for six months due to a hamstring injury she sustained in Auckland, in the first week of the year and is currently ranked No.697. On her return last week, she fell to 17-year-old Celine Naef in the first round of 's-Hertogenbosch.

There were early worries that Williams' body would let her down again when she took a medical timeout leading 3-2 in the first set, returning to court with her right knee strapped.

"I got off to a great start, and my leg started hurting in the third game," Williams explained. "I was like, 'Oh no, not this.' It was really hard to control my emotions, to be honest. Eventually I just acclimated to what I was going through and tried to ignore it. I couldn't move as well as I wanted, but I tried to get to every ball that I could."

There was no let-up in Williams' intensity over a wild contest that saw momentum shift back and forth. Giorgi chipped away at her quick double-break lead in the first set, eventually forcing a tiebreak which Williams seized with a spectacular backhand pass.

In the second set, the roles reversed. Giorgi hammered a backhand winner to take a double break lead herself for 4-1, only for Williams to attempt the comeback. The seven-time major champion retrieved one of the breaks, and serving at 3-5 saved a set point to hold after a four-deuce tussle. But Giorgi snuffed out any hope of a straight-sets win for Williams, levelling the match with a trio of one-two punches and a forehand winner.

Vintage serving from Williams saw her dominate the first half of the decider. She powered out to a 5-2 lead without facing a break point, but had to hold off a determined comeback attempt from the World No.48. A superb pass from Giorgi prevented Williams from serving the match out, and though the Italian never led in the ensuing tiebreak, she constantly nipped at Williams' heels with her easy power.

But it was Williams with more control at the end. She varied her play in the home stretch with delicate net play and clever use of the slice, and committed just one unforced error in the deciding tiebreak.

Next up, Williams will face another barrage of power as she takes on either No.2 seed Ostapenko or 18-year-old Linda Noskova. The last time Williams won consecutive matches was her run to the 2019 Cincinnati quarterfinals.