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The Italian had to rally after a tough start in his first grass-court match of the season but prevailed 6-7 (8-10) 6-3 6-2.

Despite forcing a tie-break in the first set, Sinner threw away a 4-0 lead during it, unable to hold off Griekspoor's late charge.

Sinner soon found his footing in the second and got a vital break to swing momentum in his favour, holding onto it into the third to take the win in two hours, 22 minutes.

He will face Fabian Marozsan in the next round.

The ATP World No. 1 has won 93.1% of the grass court matches played in the last six years: Novak Djokovic 14-0, Carlos Alcaraz 7-0, Daniil Medvedev 5-2 and Sinner 1-0.

Before getting the vital break, Sinner went on a run of five consecutive points to dig himself out of a whole at 0-40 down on his own serve during the fifth game of the second set, sending him on his way to the win.