Alcaraz, the defending Queen's champion and top seed, lost to Jack Draper 7-6 (3), 6-3.

For Draper, the British No. 1, it was the biggest win of his career. He was impressively composed in front of his home crowd.

Queen's was Alcaraz's only grass-court preparation last year en route to winning Wimbledon for the first time.

But this time the Spaniard will have only two grass matches under his belt following his French Open victory. Wimbledon starts in 11 days.

Draper ended Alcaraz's eight-match win streak while extending his own to seven after winning his first ATP title last week in Stuttgart.

Draper didn't drop serve against Alcaraz. They were finally separated in the first set in the tiebreak, where Draper shot to 4-0 then 6-1. Alcaraz netted a return to concede the set.

Alcaraz suffered the only break in the sixth game of the second set, after Draper's backhand return serve down the line.

Draper saved a break point to hold for 5-2, then Alcaraz saved three match points to hold. Draper served out and threw his arms in the air.

“I knew I had to come out here and play really well, and luckily I did that,” he said on court.

He faces fifth-seeded Tommy Paul in the quarterfinals.

Also Thursday, Lorenzo Musetti eliminated Brandon Nakashima 6-4, 4-6, 6-4 and will face 29-year-old British wild card Billy Harris in the quarterfinals.

Fifth-seeded Tommy Paul beat Alejandro Tabilo 6-3, 6-4.