Alexander Blockx Becomes First Belgian Man to Reach US Open Quarterfinals

Alexander Blockx became the first Belgian man in tournament history to reach the US Open quarterfinals on Monday, outlasting Argentina's Francisco Cerúndolo in a four-set battle he played through a rib injury that required on-court medical treatment. The 21-year-old's win set up a first-ever meeting with Karen Khachanov, who advanced hours earlier by surviving a nearly four-hour, five-set marathon against 20-year-old American Learner Tien that ended the teenager's bid to become the youngest United States men's quarterfinalist at Flushing Meadows since Andy Roddick in 2002.

The numbers

Blockx, seeded 28th, beat 24th-seeded Cerúndolo 6-3, 4-6, 7-5, 7-5 in three hours and 15 minutes on Arthur Ashe Stadium, according to a report on the match. He struck 36 winners and saved 14 of the 17 break points he faced against a Cerúndolo forehand that had carried the Argentine through three previous rounds. The win pushed Blockx to a career-high No. 26 in the ATP's live rankings, a remarkable climb for a player who was ranked outside the top 100 a year ago.

Khachanov's path was longer and considerably messier. The Russian, ranked No. 50 and playing without a deep run to point to this season, needed 3 hours and 50 minutes to beat Tien 7-5, 4-6, 6-7(6), 6-1, 6-4 in the fourth round, according to a wire report on the match. Khachanov lost the third-set tiebreak and appeared to be fading before regrouping to win the last two sets comfortably, reaching his seventh career major quarterfinal and his first at the US Open since he made the semifinals here in 2022.

How Blockx got here

Blockx's run is his first appearance in a US Open main draw, and Monday marked the first time he had set foot on Arthur Ashe Stadium at all, even to warm up. He described the whiplash of playing — and winning — on the tournament's biggest court on his debut in New York. The rib problem surfaced as early as the second game of the first set and forced a medical timeout with Blockx serving at 3-2, after which he leaned on painkillers to finish the match.

"I was just holding on to be honest," Blockx said afterward, describing the injury. "The doctor gave me some magical medication and that kept me going."

The victory makes Blockx, from Antwerp, the youngest Belgian man to reach a major quarterfinal in the Open era, a milestone widely reported by outlets covering the tournament. Belgium's tennis history at the majors has largely been written by its women, from Justine Henin to Kim Clijsters, making a run of this kind on the men's side without precedent for the country. Blockx had never previously been past the second round of a Grand Slam main draw.

Who else is affected

Tien's exit is the more painful subplot for American tennis. The 14th seed had been the best story of the fortnight's opening week, and a win over Khachanov would have made him the youngest US man to reach a US Open quarterfinal since Roddick's title run at 19. Instead, Khachanov's experience told in the closing stretch, with the Russian breaking clean in the fourth and fifth sets after Tien had forced a third-set tiebreak he narrowly lost.

Khachanov had arrived in New York without much momentum, having gone winless in three matches on the North American hard-court swing that preceded the tournament. That context made his description of the turnaround afterward notable — he credited an uptick in his fitness and practice habits over recent weeks rather than any single tactical change.

Blockx's win also reshapes his own head-to-head history for the week: he had lost to Tien in the final of the Next Gen ATP Finals in December, meaning a potential rematch is now off the table. Instead, Wednesday's quarterfinal will be the first professional meeting between Blockx and Khachanov, pairing a 21-year-old playing his breakout tournament against a 29-year-old former US Open semifinalist looking for another deep run.

Reaction

Khachanov, who has now reached major quarterfinals at every Grand Slam over the course of his career without a final appearance, framed Monday's win as a payoff for a difficult summer rather than any single adjustment against Tien, according to remarks carried by wire coverage of the match.

"It was a really crazy match," Khachanov said of facing Tien for the first time. "I knew what to expect: one extra ball coming back, one extra ball." He added of his form entering the fortnight: "When you are not playing well, you have to try to stay ready for the next one. I was getting more fit, practicing quite a lot and look, it paid off."

Blockx, for his part, described the day in simpler terms tied to the setting rather than the opponent. "This morning I stepped onto this court for the first time to warm up and that felt unreal," he said, "so to play a match here and win a match here is even crazier."

What happens next

Blockx and Khachanov are scheduled to meet in the quarterfinals on Wednesday at the USTA Billie Jean King National Tennis Center in Queens, with the winner advancing to the semifinals in the bottom half of the men's draw. Both players will be managing recovery: Blockx from the rib injury that flared against Cerúndolo, and Khachanov from the physical toll of his longest match of the tournament. For Blockx, ranked outside the top 100 twelve months ago, simply reaching Wednesday's match already guarantees his biggest ranking jump and payday of his career. For Khachanov, a semifinal run would match his best US Open result since 2022 and add to a resume that already includes quarterfinal appearances at all four majors but no Grand Slam title.