Sebastian Korda produced an inspired turnaround from two sets down to defeat Hugo Gaston 3-4(2) 3-4(6) 4-0 4-3(3) 4-0 in his opening match at the Next Gen ATP Finals.

The American became only the second player in the history of this event to achieve the feat, after Borna Coric against Karen Khachanov in 2017.

Korda is the second seed in Milan this year following an impressive 2021 that saw him capture his first ATP title at the Emilia-Romagna Open, and reach the Miami Masters quarter-finals and Wimbledon fourth round.

The 21-year-old looked destined to begin Group B with a defeat after losing the opening two sets on tie-breaks, while he also saved match point at 3-2 down in the fourth.

Korda subsequently dominated the final set to complete a remarkable victory in just over two hours.

The world number 39 said: "[I] just stayed calm and kept thinking what I could do better. 

"I did play very well tactically in the first two sets, but I figured a couple of things out during the tie-break and I think that helped me for the rest of the match."

Meanwhile, top seed Carlos Alcaraz enjoyed a straight-sets victory over Holger Rune, prevailing 4-3(6) 4-2 4-0.

The Spanish teenager has also enjoyed a fruitful year on the ATP circuit, triumphing in Umag while beating world number three Stefanos Tsitsipas on the way to reaching the US Open quarter-finals.

And he made the perfect start in Group A; enjoying an 88 per cent first-serve success rate in a commanding win.

"I think it was a great match, both of us played really well," the world number 32 said.

"I am trying to go to the net and play aggressively in the important moments and stay calm. I am trying to do this every match."

Elsewhere, Brandon Nakashima – champion in Brest last month – made it 10 wins from 11 matches as he beat Juan Manuel Cerundolo 4-1 3-4(3) 4-1 4-0.

The 20-year-old, who became the youngest American to reach multiple tour-level finals since Andy Roddick earlier this year, was pegged back in the second set, but dominated the final two to seal victory in just over an hour-and-a-half.

However, there was no joy for home favourite Lorenzo Musetti, who was beaten in four sets by Sebastian Baez.

Though roared on by his home crowd, the world number 58 was unable to deliver in his opening match. Baez – a five-time Challenger Tour winner in 2021 – took full advantage to prevail 4-1 4-1 3-4(5) 4-3(5).