Blockx first Belgian man to reach US Open quarter-finals

Alexander Blockx beat Francisco Cerundolo in four sets on Monday to become the first Belgian man ever to reach the US Open quarter-finals.

The 21-year-old Blockx, seeded 28th in his Flushing Meadows debut, out-lasted 24th-seeded Cerundolo 6-3, 4-6, 7-5, 7-5.

Blockx, who upset fifth-seeded Flavio Cobolli in the third round, backed up that win with a determined performance during which he received "magical medication" from the doctor to combat a "sharp pain in my rib.

"I was just holding on to be honest," Blockx said. "Even though I won that first set 6-3, it could have been the other way round."

Later, Blockx told reporters he might have retired had he lost the third set.

"I was really close to retiring, to be honest," he said. "I was just hanging in there, but I think if I would have lost the third set, I think the chances were really high of me retiring."

"Even before the match I was already under medication, and during the match I had medication. So if you feel that much pain while having a lot of medication, that's not a good sign."

But "eventually it got better," he said. "It would have been a shame if I would have retired and then it got better afterwards. I was just lucky."

The win marks the latest stepping stone for Blockx, who began the year outside the top 100 and had to qualify for the Australian Open.

After splitting the first two sets, Blockx and Cerundolo stood level at 5-5 when the Belgian fell behind 0-40 on his serve.

Blockx worked his way back with big serves and booming strokes, holding serve and breaking Cerundolo in the next game to take the third set.

A tight fourth set went with serve until Blockx gained the winning break in the final game, falling to the ground in delight when a shot from the Argentine landed out.

"This morning I stepped onto this court for the first time to warm up and that felt unreal, so to play a match here and win a match here is even crazier," Blockx said

Blockx next faces Russian Karen Khachanov, who edged 14th-seeded American Learner Tien in five sets, 7-5, 4-6, 6-7 (6/8)), 6-1, 6-4.

A former US Open semi-finalist, Khachanov beat third-seeded Felix Auger-Aliassime in the second round.