Lulu Sun knocked out of US Open with second round defeat to Elise Mertens

Lulu Sun is out of the US Open. Photo / Getty Images

Lulu Sun’s 2025 grand slam season has ended in quick time.

The Kiwi was handed a straight-sets second-round defeat to Elise Mertens at the US Open. It was her best showing at a grand slam this year, a disappointing stat after such a strong showing last season.

The Belgian 19th seed looked too strong for the Kiwi throughout the encounter on court five at Flushing Meadows, completing the 6-2 6-3 win in 80 minutes.

Sun, whose ranking plummeted to 164 in the world last week, was making her maiden appearance in the second round and her first time past the opening round at a grand slam since her quarter-final run at Wimbledon last year.

Mertens won the first four games of the opening set before Sun finally held serve in the fifth game and then broke back to make it 4-2, giving hope of a comeback. However, the world No 21 then broke Sun for a third time to take the set.

Mertens then broke Sun again to begin the second set and held the control of the match through the rest of the set to close out the win on her second match point attempt.

Mertens will face Spaniard Cristina Bucsa in the third round.