New York, Sep 8 (IANS): Canadian Felix Auger-Aliassime made his first major semifinal at the US Open after Spanish giant-killer Carlos Alcaraz retired due to an undisclosed injury 6-3, 3-1 at the Flushing Meadows.

The 21-year-old is the first Canadian man to make the US Open semifinals in the tournament history (since 1881) and the youngest man to advance to the last four at Flushing Meadows since Juan Martin del Potro of Argentina lifted the trophy in 2009.

"It's an amazing milestone. It's been a fantastic tournament for me. Of course it was a weird ending today. But in the end, I'm through," Auger-Aliassime said. "I'll have a chance to play on Friday against one of the best players in the world right now to have a chance to be in my first Grand Slam final. It's amazing, I'm happy I'm through and I'll try to win the next one," Auger-Aliassime told atptour.com.

The 12th seed will next play second seed and two-time major finalist Daniil Medvedev of RUssia, who won their only previous ATP head-to-head in a final-set tie-break in Toronto three years ago.

Alcaraz won back-to-back five-setters against Greek Stefanos Tsitsipas and German Peter Gojowczyk to make it this far. The teen was not as sharp as he was earlier in the tournament, making 16 unforced errors in 13 games. The booming groundstrokes that so often found their mark earlier in the fortnight fell into the net on Tuesday.

During the first changeover of the second set, an ATP physiotherapist visited Alcaraz and had a lengthy discussion with the Spaniard, but did not treat him. One game later, Alcaraz retired, surprising Auger-Aliassime.

"No, I didn't [know anything was wrong] until he called the physio. I don't know what happened, clearly, but it's unfortunate. I didn't see it coming. He's such a good player. You guys were amazing again tonight," Auger-Aliassime told the Arthur Ashe Stadium crowd. "I thought we were putting on a good show."